The Cross Terrain was specifically designed to provide a smooth, quiet ride. It's a great choice for those who have luxo SUV's and want the nicest ride possible.
The LTX M/S is like and 80/20 tire - 80% on road and 20% off road use. Depending on the type of vehicle they're installed on and the road conditions, you may or may not notice a difference in road noise. The LTX typically lasts longer, mileage wise (treadlife warranties notwithstanding).
"Cross Terrain's a passenger car tire? Dunno how you came to that conclusion. Look at how Michelin positions the tire in the marketplace:
link title
Click on "View detailed sizes..." for a PDF of the tire's specs.
Are we talking about the same tire????? "
No, but I was answering another post for a different web site!
My error in transposition!
I had a few too many windows open and was also doing some research on the CT and TT" that is: Goodyear Comfort Tread and Triple Tread, Passenger tires of course.
but I finally got a look at my truck's Michelin tires in the daytime...you may recall I have a 2004 Ram 1500 Quad, where Dodge calls for 35 psi cold as standard tire pressure, and the Michelin LTXs state a max psi of 35, so we have a quandary...someone asked me what the tire actually said, and it says "Max Press (metric stuff) 35 psi"...so we have some posters here (experts?) saying that it doesn't really mean that (what do I know?) and the tire dealer saying it means exactly what it says...what would "Max Press 35 psi" mean to you, and why would one interpret it any other way???...having asked that rhetorical question, why would Dodge recommend a tire pressure that was the max psi on the tire they bought for the truck???...was anybody paying attention when they received the cheapest tire quote from the manufacturer???
The Michelin LTX line, you need to pay a tad more attention in that it is all over the map, (given different sizes)
So for example the Michelin's listed on tirerack.com indicate max sidewall pressure for Michelin LTX for 275-70-15 S rated is 35 psi. Same size only H rated is 44 psi. On my Toyota Landcruiser (S R'd tires) it recommends 32 psi, so I run 35 psi and the most I ignore it is when it gets down to 32 psi. (given Michelin LTX S rated)
So for me there is a subtle adjustment with the new Bridgestone AT REVO's that have a max sidewall pressure of 44 psi (S R'd) I usually run it at 85% or 37/38 psi.
>You wrote: “ Dodge calls for 35 psi cold as standard tire pressure, and the Michelin LTXs state a max psi of 35, so we have a quandary ”
I don’t see a quandary, but perhaps there may be some misunderstanding on your part (or even possibly -- heaven forefend! -- on my part.) ;-)
>You wrote: “ why would Dodge recommend a tire pressure that was the max psi on the tire they bought for the truck?”
Because they judged that this is the appropriate pressure for this tire on this vehicle. I doubt there is any conspiracy to be found here. It’s really quite straightforward.
Dodge specified a tire, and recommends running it at a pressure within that tire’s specifications. True, there’s no headroom for running higher pressures to alter the handling, for instance (albeit with harsher ride), but Hey! they gave you what works. Right?
Was it the cheapest solution? Probably. So, what’s new? ;-)
By the way, auto manufacturers tend to specify original tires that meet their needs, not yours. One of their greatest needs is to achieve better fuel economy ratings. Tires that yield the best fuel economy ratings tend to be very poor performing tires in most other respects. These tires are still reasonably safe, you understand, but they don’t provide the best grip, for example. Better grip means stickier rubber, and stickier rubber means greater rolling resistance, which, in turn, means lower fuel economy and so forth.
OEM tires are notorious for annoying just about all discriminating motorists. The automotive after-market is grateful for this. ;-)
Can you purchase a better tire than the OEM? Almost certainly. As ever, performance costs money. How much would you like to spend?
However, before you go down that road, you might wish to ask yourself what your goals are, and what you hope to gain by spending more. It is possible that the OEM tire actually gives you all you really need. I don’t know your needs, of course; just a thought.
For example, I’m sure everyone could benefit by fitting their cars with a max performance tire. But are their daily needs consistent with such a purchase? No, of course not, especially not when one considers the overall cost of such a tire -- summer only, short life, noisy, hard-riding, much more expensive, etc.
Now, me? Well, I just bought a set of max performance tires on lightweight wheels, but I’m not everyone and my needs and desires may, indeed do, differ from the majority. It was the right choice for me at this time. YMMV.
It’s all a compromise amongst many elements, and there is no “correct” answer, just answers that may better fit your particular needs, whatever those might be.
It’s your money, your car/truck, and your decision. Choose wisely.
>You wrote: “ what would "Max Press 35 psi" mean to you?”
Why, just what it says, of course! Why would anyone think otherwise? The manufacturers aren’t trying to trick anyone here, for heavens sake. The legal liabilities of such “trickery” are frightening to contemplate!
It means just what they say: Don’t blow this balloon up beyond 35 psi, or you risk blowing up this balloon! It’s very simple.
So, when your tires are “cold” (see below for more on this), inflate them to 35 psi, and no more. Now you’re good to go. Fear not and enjoy your truck! :-)
Does this mean that this tire will blow off the rim, or explode at 36 psi? No, of course not. There is headroom built-in, not for least which reason is the need to accommodate the increase in pressure accompanying the increase in internal tire temperature as it rolls down the road under load -- friction creating heat, which warms the internal air, which expands as all gasses do when heated, and the pressure increases concomitantly. (Note, too, that tire pressure varies with ambient temperature. Thus, a ten degree F increase in ambient temperature will result in a one psi increase in tire pressure; a reduction in ambient temperature of ten degrees will reduce tire pressure by one psi, and so on. One psi change for every ten degrees F temperature change. This is an important safety issue when the seasons change, or in the high desert and similar climes. See below )
“Cold inflation pressure” is too often misunderstood. Sometimes it’s even misunderstood by the “experts” offering advice. (Present company excluded, of course! ;-) For instance, I suggest you go to the Tire Rack website (an excellent source for tires, by the way, and my choice) and while there, read their numerous technical articles on tires and wheels and such. The articles are generally good. However, note that their explanation of cold inflation pressure is flawed -- just flat wrong. They say “cold” means inflating in the morning before the heat of the day builds up.
No! That’s ridiculous! “Cold” means the current(!) temperatures you’re actually running in, not the freezing early morning temperatures! Geeze! What if you live in the high desert with its dramatic temperature swings between midnight and midday?!
Here’s my notion of a good definition of “cold inflation pressure”: The air inside the tire is at the same temperature as the air outside the tire, when the tire is in the environment in which one will be running.
How’s that? I like it; what do you guys think?
When is this the case? When the tires have been setting undriven for hours, probably four or more hours, and in the environment in which you plan to drive. (Not in your air-conditioned garage/workshop, for instance, but outside where it’s hot in the summer; or, colder in the winter!)
Even a slow drive in town for one mile will heat up the tires and yield a false “cold” inflation pressure. (Yes, this can be accounted for, but I’m trying to keep things as simple as possible here for the moment.)
Does the above make sense to you? It’s difficult trying to write posts that provide clarity.
How’m I doin’ so far? :-)
That’s not rhetorical, I’d appreciate some feedback from any of the readers here. I’m not here to be a know-it-all; I don’t come here to put people down. I’m trying to share my hard-earned knowledge with others so that they might be better informed. If I’m not doing well, you’d be doing me a great favor by helping me understand my shortcomings.
-Kauai (who asks for no more than a courteous “thank you” for his efforts, and who unfailingly thanks others for theirs.)
So it actually says "max pressure 35 psi" and not "max load XXX at 35 psi". Interesting!!
So to answer your question - "why would one interpret it any other way???" If you understand the engineering standards, then you can interpret it differently, but if you don't, then don't interpret it - follow it.
"why would Dodge..." From an engineering point of view, there isn't a conflict. The max is the max (don't forget that the actual load on the tire is probably not the max load). However, if you are questioning the engineering judgement of the guy that approved this, then you have to understand the engineering standards for tires - which leads us back into the circle of logic. Either you accept what is written on the sidewall as gospel, or you have to understand ALL the engineering behind the product - including reserve capacity, exceptions to the max pressure, etc.
The Michelin LTX M/S 265/70-16's that I had 63K miles on it were still fairly quiet, but please keep in perspective that this is my first pickup and those were the original tires. As such, I have no point of reference to compare by.
Now, the Cross-Terrain SUV tires I got yesterday seem to be a little noisier, but this is in contradiction to what Michelin should be the case (they should be slightly more quiet). As such, I think a new set of LTX's probably would have been as loud or slightly louder than a new set of CT's.
So far I've got about 150-miles on them and they seem to be doing ok. I also need to follow/interpret the tire pressure according to Michelin since 'they' made the product.
That is the "cold inflation pressure" meaning I use as well. Actually, I drive 3 blocks to a local gas station with "air" (this is getting rarer these days), and check and inflate there. If anyone else does this, be sure to drive at slower speeds, and keep the distance short. The tires do heat up quickly, though even if they heat up by 10-20 deg. I suspect the difference would not be noticeable, as tire gauges and their use is not accurate enough to reflect a 2 PSI difference.
Something else I do is always use my own tire pressure gauge as the final "standard" - I keep it in the glove box - and each vehicle I own has one. I watch my tires wear, and if I am over inflating (indicated by more wear in the centre of the tread) I reduce the pressure based on my gauge, and if under inflating (indicated by more wear on the outside of the tread, allowing for excess wear due to fast cornering and alignment errors - something that must be learned by experience) I increase the pressure, again based on my gauge. After a year or so I learn the correct inflation pressure for each vehicle and my use. Gauges can vary and the "correct" inflation pressure you use (not the max) can also vary slightly from the manufacturers recommendation.
Here in Alberta we see a large ambient temp variation (down to -50 C occasionally in winter, typically -20C and up to +40C in summer, typically 30C - and occasionally in spring it varies from -20C to +20C in a single day! It makes tire pressure control entertaining ;-) . Especially when you want to check the tires in the winter, chipping ice and snow out of the way, and trying to find a tire pressure station that hasn't frozen due to condensation in their hose!
The temperature swings within a 24-hour period in Alberta are just the sort of thing I was thinking of. Imagine on the day when the temperature varies from +20C to -20C that one sets the tire pressures at +20C. Then one finds oneself out driving about later at -20C. The temperature drop was accompanied by a very serious drop in tire pressure, arguably so low as to be deemed dangerous, and certainly not good for the tires. Clearly, that’s an extreme and probably doesn’t happen very often.
By the way, there are in fact tire pressure gauges that are more accurate and consistent than you may be accustomed to using. Autocrossers, road racers, etc. all require much greater precision in their gauges so that they might tune their handling reliably and consistently by adjusting tire pressure. However, they might be seen as too expensive for the average motorist; mine sells for $50, and it’s a big dial gauge bleed-down model too big to fit in my glove box with other items.
Another tool autocrossers require is an air tank, not a compressor, just a tank. I got mine at Wal-Mart for $18. I fill it up to 120 psi at our local village gas station and have my own air whenever I need it. I bought it when we got into autocrossing, where tire pressures are critically important and a 2-psi change can make a significant difference in a sport where positions may be won or lost by hundredths, if not thousandths, of a second. Drivers are forever adjusting tire pressures on the grid throughout the day, and an air tank is a necessary part of one’s toolkit.
Once I got this inexpensive air tank, I kicked myself for not getting one decades earlier. If you also have the luxury of a garage, it makes maintaining one’s tire pressures in the winter a breeze. For those who diligently maintain their tire pressures, an air tank is a must-have; if you buy one, you’ll be glad you got it.
A word of warning for those folks who are using tire wear to determine inflation pressure.
Inflation pressure = load carrying capacity. So care must be taken that enough inflation pressure is in the tires to carry the load put on them. Otherwise the tire would get a fatique failure - not a good thing when it happens.
The second thing is that most vehicles will create different wear patterns in the front than in the rear - but the tire pressures are typically specified as the same front to rear (but not always). The vehicle manufacturer spec'd the springs, shocks, and sway bars based in the way the vehicle reacts with the specified inflation pressure. Changing the inflation pressure, especially the front to rear split, might cause some unanticipated handling issues, especially in emergency manuevers - just when you want the vehicle to behave predictably.
And last, but not least - The steering end of the vehicle typically causes the shoulders of the tire to wear faster than the center. Some incorrectly interpret this as too much inflation pressure. Typically, the rear tires wear in the center, which all gets balanced out if the tires are rotated regularly.
A good dose of caution and common sense goes a long way in this area.
I think you guys/gals are bring up real good points. Being an old bomber and fighter operations type, it is interesting to note that racers of all types have take formerly aviation type (barometric and other weather type) readings!
So I do appreciate the discussion, for there are a fair amount of points! So I am of the variety that knows that I don't know enough. So if it triggers a type like that to do the required research, then that is a good thing!
But I think when it comes to T/P , the VAST majority might be classified under the "I have ignored it long enough" type category.
I would certainly like to thank all of y'all who responded to my query, especially kauai who virtually composed a PhD thesis online...in terms of cold psi, I usually overfill my tires at night, let them sit in the driveway and let out air in the morning before the sun hits the truck...I do this 1-2X monthly...as far as my quandary, my only reason for asking was that it did seem odd to me that Dodge would install a tire, as you point out, whose recommended psi is where the max would be for the tire...most of my past vehicles had reco psi of 30-32 psi cold, so a tire with a max press of 35, 38, or 40 seemed logical, meaning that the tire was not inflated to its max pressure when inflated for the car on which it was installed...is it not odd to you that Dodge would reco 35 psi, but that they would call for a tire whose max was 35, leaving no leeway, leeway being something I have always seen on EVERY car I have owned since the 1960s...not wanting to be an anal-retentive lawyer, but theoretically, IF something went wrong a la Explorer/Firestone, if I inflate to 38 psi, someone from Michelin WILL testify to a jury that I obviously can't read because it says 35 max right on the tire, and if I inflate only to 32 psi, someone from Dodge WILL testify that the decal right on the door says 35 psi, if I would only learn how to read...not having leeway just "seems" like the wrong tire is on my truck...does anyone see this, or am I just a bona-fide idiot???...thanks again for those detailed responses...
Do any of the sealants in a can work? I had a flat on my Altima last winter, and installed a full can of Fix-A-Flat, per the instructions. It went about five miles before the tire was flat again. I aired it up with an air compressor, and went another mile or so before I had to get out in the freezing cold and install the spare. The puncture was in the range of 1/16" - 1/8". To add insult to injury, as the sealant exited the tire, it slung all over my car's paint, and the stain required a clay bar to remove.
Are the OEM-supplied "flat kits" on high performance cars with no spare (M3, Mini, Corvette) any better than this?
If you get a guy from Michelin to testify as you've indicated, you'll get 10 guys who will testify to the opposite. I'll even go so far to say that no one at Michelin would step in that pile - for the technical reasons I've outlined earlier.
I'll even go farther: There are some very good technical reasons to specify the maximum. For example: If the vehicle engineer, who is working 2 to 3 years before the vehicle is launched, is sizing tires, he would estimate the load on each tire. If his estimates resulted in a minimum of, say, 33 psi, then picking 35 psi would give him room for error. Plus using 35 psi makes the speed rating applicable as it is - no need to derate it. Knowing that many folks don't check their pressures, this is additional safety.
All this would be very important for a truck, which just might get loaded up with supplies from the garden center or the lumber yard - unlike a car which this scenario is very unlikely and where ride comfort is a very important consideration.
Plus going to a larger tire, with a lower inflation pressure, means more cost - and it's not just tire cost. Larger tires means larger wheels, wider fenders, beefier suspension, etc. All these things add up - so we may be talking about a couple of of hundred bucks to use what seems to be something unnecessary.
(If you’re not up to this, please press the Page Down key, now. You’ll get past this eventually.) ;-)
>You wrote: “I would certainly like to thank all of y'all who responded to my query, especially kauai who virtually composed a PhD thesis online...”
You’re welcome. This man will take that as a compliment. You’re a scholar and a gentleman, sir, and I thank you. :-)
>You wrote: “ and let out air in the morning before the sun hits the truck ”
Aha! You’re thinking that the radiant energy from the sun will heat up the black tires on the sunny-side of your truck, increasing the pressure in those two tires, but not the offside tires, right? Now, if you adjust them so that they’re equal, left and right, they’ll be unequal after reaching operating temperature. I like the way you think; the details are important.
I checked that very phenomenon on one of our cars, and sure enough, the sunny-side tires were 1-psi higher than the shady-side tires after a short while in the direct sun, whereas they had been exactly equal in the garage shortly before. (You already knew I’d done that, didn’t you?) ;-)
I enjoy sharing my meager bit of “knowledge,” such as it is. :-)
>You wrote: “ most of my past vehicles had reco psi of 30-32 psi cold ”
Yes; mine, too, although I have no experience with trucks, as we prefer sports/GT cars.
I wonder if, perhaps, the correct minimum everyday tire pressure for your truck might be 30-32 psi, or even less, with the large-volume tires? But, maybe, Daimler/Chrysler decided to instruct owners of this Dodge truck to run the max pressure all the time -- just to be on the safe side, for you and for them.
So Dodge might have recommended, say, 30-psi, along with recommendations of a 3-psi increase for load and higher speeds, while still leaving 2-psi headroom. Instead, they said “No. We don’t trust folks to maintain the tire pressures near the minimum safe levels, so we’re recommending the max, 35-psi, as the minimum.”
Just a bit of forgetfulness, coupled with normal air loss of maybe 1-psi per month, added to a 40 degree F drop in temperature and you’re easily 5-psi low, down to 25 psi (if you started at 30-psi about a month before.)
With only 25-psi in the tires, sudden evasive maneuvers could easily result in a rollover crash in a tippy truck or SUV. It happens all the time, unfortunately. Many folks are living on the edge -- teetering on the brink, so to speak -- and just don’t know it. One need only get that tall mass on an SUV or truck to swaying mightily, heaving to one side and then abruptly back to the other side, exactly as it happens in a violent evasive swerve to the left to avoid something, followed by an equally violent swerve back to the right (to stay on the road!), exacerbated by the likely oversteer slide that began with the first sudden braking/turning maneuver to the left (never brake hard and turn simultaneously if there’s any way to avoid it), and (the driver’s probably cooked by that point, but just doesn’t know it yet) that final pendulum swing back in the opposite-slide direction to the right, and ooopsie daisy -- over you go onto your head. You’ll be unhappy.
Instead, though, Dodge has recommended 35-psi for the minimum, everyday tire pressures, hoping to avoid the dangers of inadvertent low -- and dangerous -- tire pressures. This makes the ride harsher than would be absolutely necessary much of the time, but “ensures” that the tires are always at “nearer” maximum pressure to resist rollovers, carry extra loads, etc. No doubt, their likely mistrust of owners to maintain their tire pressures responsibly is a factor as well. They want to avoid any problems like the Ford/Firestone debacle (which was a tire pressure problem, not a tire problem, attributable to Ford foolishly recommending a normal tire pressure in the mid-to-upper twenties, as I recall. Softer ride, you know Now, they insist on around 35 psi, as I recall. Sound familiar?). If 35-psi means you Dodge owners ride around much of the time with harder-riding tires than absolutely necessary, well they don’t care. Can you blame them in this litigious society? ;-)
That might help to logically explain things. Is it right? I have no idea. I’m just speculating as I try to account for this rather odd business. I agree with you, you see; it’s not only odd, but it would leave me feeling the same unease that I sense you are experiencing.
I suspect that the relatively narrow-track, tall-and-tippy trucks and SUVs of today are actually hurt by modern, grippy tires. Today’s tires stick too well, generating g-forces unheard of in decades past. These higher g-forces probably contribute to rollovers. Tires from the past would just slide helplessly (which carries it’s own set of problems, obviously), rather than generate the g-forces sufficient to roll these vehicles over. And everyone seems to want big, wide, meaty tires, for that extra-aggressive look, giving yet greater grip, which is just what one doesn’t need in those tippy-mobiles. Unintended consequences, eh?
As I’m writing, it occurs to me that maybe Dodge deliberately selected the least grippy tire it could find, precisely to obviate the rollover dangers. Such a tire is one I would expect to see with an unusually low max pressure. Who knows?
You could try calling Chrysler corporation, but could you believe anything they said to you? Just another of Life’s Mysteries, I reckon. ;-)
I don’t know much about trucks, nor truck tires for that matter. However, from what I’ve read, the suggestion seems to be that much of what applies to car tires is also applicable to light truck tires. Apparently, many car tires can be used on trucks.
Please do correct me if I’m mistaken as I pursue my thoughts here. Some folks (to my everlasting amazement) would rather be wrong than be contradicted. Try to educate them, and they take offense. (That’s why I let many writers’ assertions, which are clearly false, just slide on by. I don’t need the aggravation of dealing with their “ungrateful” response. I prefer peace to combat, thank you.) They actively embrace ignorance. I’ve never understood that, but I suppose it’s part of the macho/BS, perpetually competitive, striving-for-ascendancy-in-the-pack, sort of thing. That’s not my way. Please tell me when I have it wrong -- I’ll be grateful, not angry and hostile.
>You wrote: “ so a tire with a max press of 35, 38, or 40 seemed logical, meaning that the tire was not inflated to its max pressure when inflated for the car on which it was installed...is it not odd to you that Dodge would reco 35 psi, but that they would call for a tire whose max was 35, leaving no leeway ”
Herein may lie a misunderstanding: Your words seem to carry the implicit assumption that load-carrying capacity increases with pressure up to the maximum permissible tire pressure.
That is a false assumption, albeit eminently reasonable, especially given the manner of displaying information on the tire sidewalls.
What is interesting, and a long-time puzzle for me until recently, is what is stated on the tire sidewalls. For instance, on the new tires I just bought, it reads: “Max. Load 1235 lbs. @ 51 psi Max. Press.” (I’ve omitted the metric data that’s also there.)
Strictly speaking, this statement is true. But, the assumption that 51-psi is necessary to achieve that load capacity is false. Yet, that’s exactly what most folks are likely to conclude with this “misleading” statement. This odd statement on the tire sidewall too readily permits misunderstanding, and if I were King, I’d order this practice changed. ;-)
My new tires are “Standard Load” tires (a.k.a. SL), and by international agreement in the auto industry, all SL tires shall reach their full load carrying capacity at 35-psi, regardless of whether they are also made stronger to tolerate even higher pressures safely.
(Do you see the glimmer of light ahead?) ;-)
There are two issues here: (1) Maximum load capacity, and (2) Maximum pressure. They are related only up to a point. Max load capacity is reached at 35-psi, and the extra pressure permitted (if available), allows the user, for example, to adjust the front/rear balance of grip, or give some added safety (I think) running at high speeds as it makes the tire less flexible, thus generating less internal heat, and internal heat is the enemy of tires.
From a FAQ on the Yokohama Tire website: “A Standard Load tire may be branded with a maximum inflation of 44 psi, indicating the tire's ability to meet special performance requirements. It does NOT increase the tire's load capacity.”
Note, too, that there is also an “Extra Load” (XL) rated tire, which achieves max load capacity at 41-psi, again by international agreement. Most tires for autos seem to be SL rated.
Again from the Yokohama FAQ: “Extra Load tires are limited by the load that can be carried with a maximum inflation pressure of 41 psi. An Extra Load tire will be branded with 'Extra Load', 'XL' or 'Reinforced' on the sidewall. A Standard Load tire does not bear any special identification.”
What they’re saying here is that an XL tire reaches it’s max load capacity at 41-psi, even though it may have a stronger design that permits even higher pressure capacity. Beyond 41-psi, an XL-rated tire does not increase the load capacity.
The 35-psi max pressure on your Dodge truck tires would suggest that they are SL tires, not XL tires, which are what I would have thought would be the more sensible choice for a light truck. Who would make an XL tire, but limit it to 35-psi? But, what do I know?
And, if indeed your tires are SL tires, additional pressure capacity would not yield any greater load carrying capacity, the max load capacity being reached at 35-psi.
“But, still ,” you’re probably thinking. Yeah, me, too. ;-)
Parenthetically, for those of my readers who still labor under the widely held misconception that the tire manufacturer determines the appropriate tire pressures front/rear on your particular car you may wish to read the following for your edification:
Again, from the Yokohama Tire FAQ on the web: “The maximum pressure for a tire is always indicated on the sidewall. This maximum pressure should NOT be confused with the vehicle manufacturer's recommended tire pressure. The vehicle manufacturer information is listed on the Tire Information Placard located on the door post or glove box lip, and is also contained in the Owners Manual. ALWAYS follow the vehicle manufacturer's information.” [Yokohama’s capitals, not mine.]
At first glance, the notion that the tire maker knows their tires best, since they made them, after all, seems to make sense. However, this is irrational if you extend the reasoning. Consider: How many different year, make, and model of cars are roaming the planet? Never mind the additional complication of multiple tire choices on many of those models. Any given manufacturer’s tire might fit an awful lot of this myriad number of cars. Indeed, many different models of tire from, say, Bridgestone, would fit any given car. Who’s going to compile and keep current the necessary database of information for front and rear tire pressure for each and every one of those cars, and for each of the many models of Bridgestone tire that will fit? What happens when new models appear? Moreover, how do you propose they should squeeze all this advisory information onto the tire sidewall? The sheer volume of data is staggering. I really cannot see how the tire manufacturer can manage to squeeze all of that onto a tire sidewall. Can you? If so, you’ll have to tell me how. And how would I read it? Do you see the difficulty, folks?
The VEHICLE manufacturer designed the car and specified the tire. Between engineering computation, empirical testing, etc. THEY decided what pressures to recommend. The tires they selected as part of their design are part of the suspension system in a very real sense (sort of an air-spring). For the automotive engineers, tires are an integral part of the design of the car. They are not generally just an afterthought.
Although, having said that, there is the interesting case of our friend’s Dodge truck here, which may belie that assertion. Well
Note, too, that in his odd case, the max pressure is also the recommended regular running pressure. (That’s just a coincidence; don’t be mislead.)
What were they thinking at Daimler/Chrysler when they put together our friend’s truck? Probably a case of the Bean Counters over-riding Engineering, with Legal somehow left out of The Loop, else Legal would probably have blanched at the prospect of a marginal tire and commenced bleating loudly, foretelling catastrophe and doom But, what do I know?
Anyway, my friends, one should set tire pressures to what the CAR manufacturer recommends. It’s best to regard those pressures front/rear as a minimum. There are excellent reasons to exceed that minimum, though. For instance, on my P5 (recommended 32/32 F/R) I run 37/35 F/R as my regular pressures. The Dunlops on this car have a max pressure of 51-psi. It would be a mistake to run 51-psi in this car on the street.
My current tires (and recent tires) have a max inflation of 51-psi. Recommended pressures on our Si are 33/30 F/R, and on the Protege5 are 32/32 F/R for normal use. Both manufacturers recommend 3-psi higher for heavy loads or prolonged, higher interstate speeds. That still leaves an awful lot of headroom, far more than anyone would likely use in normal use. In fact, I’ve run 55-psi in the fronts on the Si when racing. This is hardly applicable to street driving, and running “even” 51-psi is wildly impractical and one is more likely to damage the tires at those rock-hard pressures than assist them. Not much “spring” left in the tire at 51-psi to absorb bumps and sharp things. Besides, 51-psi provides a ride quality on the street that quickly generates unhappiness.
Returning to the Dodge truck issue, and proceeding apace
>You wrote: “ is it not odd to you ”
Yes, it is. And in the unlikely event I were to own a Dodge truck similarly equipped, I’d be unhappy. I’m just trying to help you see that what Dodge has done here is not necessarily “wrong.”
But it sure seems like they’re skirting the edge of “wrong-ness” here, doesn’t it? This may be taking cost-cutting measures a wee bit too far. I confess I’d want to replace those tires with something more to my liking.
And also, had Dodge recommended, say, 30-psi for your truck I’d have encouraged you to inflate them to the 35-psi max, and religiously keep them there for the rest of your life, checking them weekly and more often when temperatures change markedly.
>You wrote: “does anyone see this, or am I just a bona-fide idiot???”
I see it, and “No,” you’re not. Again, I’m with you. ;-)
My tires are my lifeline, my connection to the road; as they go, so go I. After all is said and done with the drive-train and the suspension and the aerodynamics and it all comes down to what’s happening at those four small patches of rubber, the interface between the rubber and the road. I take my tires very seriously.
Driving your heavily loaded Dodge truck would leave me feeling I might be “pushing the envelope” at speed on those tires. I wouldn’t like that. ;-)
Well, Bob, (or is it Marsha? I’m confused.) I hope this has helped.
Feel free to ask further questions, and I’ll answer as best I can. Who knows? Chapter 3 might be forthcoming you never know your luck! ;-)
-Kauai (an old fart who hopes that, at the very least, he put a smile in someone’s day.)
To pick out one little point in your disser...er, message , can one then attribute (partially) "curb tripping" to underinflated tires.
Swerve, swerve, trip, roll?
Then we get into the question of whether SUV tires could be too grippy causing a trip.
Tire pressure monitors are coming soon. How much more expensive would it be to hook the tires up to a compressor for real time or periodic inflation adjustments (could you even do it real time with the pressures expanding from heat as you drive?).
How much does the inflation option cost in the HUMMER?
I must print your thesis so I can read it in my easy chair, looking at my monitor makes me dizzy...scanning over it, you do make some good points...but I chuckle at my own ignorance and for causing such a stir in what should be a simple subject...at the risk of oversimplifying, I just feel better on my 2004 Crown Vic, which has Goodyear Eagle LS tires, the reco from Ford says 35 psi cold, and the tire says max press 44 psi...in my childish, simplistic mind, I just feel comfortable filling to 37 psi cold, to allow for 2 psi leakage and still maintain a firm ride, and my 37 psi setting is, in my ignorant mind, still simply 7 psi below what I believe to be the tire's max safe inflation pressure...if my truck did the same thing my life would be simpler...and I like things simpler...I also notice that you space your paragraphs well, so you will NEVER have to worry about the "Poster's Paragraph Police" which attack me constantly for run-on paragraphs...of course I am guilty of their charges, but I always feel that the "flashing blue lights" are over my shoulder as I post...such insecurity...:):):):):):):):):)
*** How much does the inflation option cost in the HUMMER? ***
It's standard on the H1 now. I think it was pricey, at least $1000, before, and the older iteration included goofy plastic adapters for the valve stems. The current version is more seamlessly integrated with the wheels.
Whoa. You mean there are cars with built-in tire inflation capability to obviate the need for the local gas station air compressor or the handpump at home!!!
One of the minivans had (has?) a built in compressor and hose in the back. But you have to leave the car to inflate the tires (life's tough!). Great for river rafters I suppose. Any car with air adjustable suspension should have a compressor buried somewhere too.
>You wrote: “ can one then attribute (partially) "curb tripping" to underinflated tires. Swerve, swerve, trip, roll?”
I’m uncertain what you mean by “curb tripping,” and I’m no expert, but of the interpretations that come to mind, I’d think, “Sure!” In fact, I’d think under-inflation is a major contributor.
It seems reasonable to me; don’t you think so, too?
>You wrote: “Then we get into the question of whether SUV tires could be too grippy causing a trip.”
Yes, although I wonder if you’d agree with me if I shifted the emphasis a bit. I would suggest that the grippy tires are not at fault; rather the inherently unstable vehicle is at fault, while the grippy tires just exacerbate this problem. The SUV is the problem, not the tires.
It might be a good idea to refrain from putting, say, Potenza S-03 Pole Position tires on the typical SUV!
I imagine a “skilled” driver could force many of today’s SUVs to roll despite the tires being inflated to the maximum. Get that huge, tall mass to heaving about, and with the angles of lean that are generated, even a properly inflated tire will roll the shoulder under significantly which further exacerbates the lean and onto-the-roof-you-go.
I recall reading a piece in one of the auto magazines a number of years ago where the writer was describing his experience road testing an SUV. I don’t recall what the make and model was, but I don’t believe it was one of the ones that had a notorious reputation for rolling over. Anyway, the guy was running this SUV through the cones they set up as a reference standard for all their road tests.
Now, I think it’s fair to assume they had the car properly set up, with appropriate tire pressures, etc.
He rolled it onto his head! In “normal” driving while running it through either the sudden lane change test, or the slalom, I think. He was under control until he was suddenly on his head!
He was wearing a helmet, fortunately, and his seatbelts, of course. What I recall most was his description of how sore he was from the beating he took in the relatively low-speed rollover. He was clearly hurt.
When I was teaching my wife to negotiate the slalom in autocrossing, I recall I concocted this little ditty to help explain a point, and now I can add a bit for SUV drivers: [Sung in a sing-song manner with a metronomic cadence and swaying left to right.]
* * * * * * * * * Left, right, left, right, dancing with the cones; Left, right, left, right, onto the roof we GO!
Well, never mind
Lots of folks have suffered rollovers through no particular fault of their own. They’d maintained sensible tire pressures, etc., but evasive maneuvers alone put the thing on its head. These are inherently unstable vehicles. I would not drive one, much less own one.
But, I’m not looking for a fight with the folks who love their SUVs. I wouldn’t seek to deprive you of them. They’re just not for me, thanks.
And I try to steer clear of them whenever possible. ;-)
>You wrote: “Tire pressure monitors are coming soon.”
Yes. They’ve been here for years, but now the government is requiring them on all new vehicles starting next year, I think? You can order them from the Tire Rack today, if you like.
I don’t know where tire pressure monitors saw their first use, but I recall first seeing them used on Indy cars some years back. Very useful for high-speed oval racing, where a tire can start to go down, but the centrifugal force of the rotating tire at 200 mph keeps the tire looking “normal” until it’s too late. I would think that suffering a tire failure on the wrong side of 200 mph would be very upsetting.
I seem to recall that Jaguar, I think, has this system in place on at least one of their sedans, and the Autoweek long-term testers were having problems with it. I could be mistaken.
I anticipate it will be a few years before these monitors become consistently reliable, and the consumer complaints die down. We’ll see
One of my concerns is that the states will commence checking on the functioning of these mandated monitors when they do the annual vehicle emissions testing, and we’ll be required to pay to repair the miserable things. It’ll probably cost a lot, removing a tire, or two, replacing the sensor/sender strapped to the center of the rim, remounting and balancing the wheel (probably damaging our nice alloy rims in the process), and we’re going to be furious.
The government is a bit too “helpful” for my taste. There are some kinds of “help” I can do without, you know?
Take care, folks, keep an eye on your tires, and, as AAA used to say, “Bring ‘em back alive!” :-)
-Kauai
“I am not young enough to know everything.” -Oscar Wilde
***I recall reading a piece in one of the auto magazines a number of years ago where the writer was describing his experience road testing an SUV. ***
I think it was a Jeep Liberty in AutoWeek. IIRC, the test driver did not walk away unscathed, either. I remember that the instability plus injury really turned me off to the Liberty.
***Jaguar, I think, has this system in place on at least one of their sedans, and the Autoweek long-term testers were having problems with it. I could be mistaken. ***
A Jag with electrical gremlins, can you imagine? :P
***states will commence checking on the functioning of these mandated monitors when they do the annual vehicle emissions testing, ***
I don't care much about the emissions testing, but wish all states had vehicle inspections. It's not required in my state, and I see tons of bald tires, burned out lights, and busted windshields, and the police never stop people for these offenses.
I would purchase an SUV, if it were responsive and fun, and included stability control. Something like an X3/X5 or M-class on the high end, but they're way out of my price range. I've driven a current model Yukon, and it was one of the blandest, most uninspiring things I've ever driven. Stability control should counteract a tire that is too grippy by braking the car if you're going too fast for a corner--allowing the enjoyment of a high-performance tire on an SUV while minimizing the risk of rollover that it might induce.
The RX-8 had them last year and still does - in the US. We didn't get them in Canada. From what I've heard from owners, they seem to work just fine - though some owners were upset that they actually had to add air "or else" (the system makes some noise if you are lazy). It seems the hapless can't even be protected from themselves with electronics!
The funny part is they are wireless (of course), and Mazda warns if you are parked beside another RX-8, it can confuse the system as it will see all eight wheels. Not to worry, they say. It will regain its' composure as you drive away.
They increase the cost of "winter wheels", and most owners just use wheel/tire combos without the sensors and ignore the red light during winter.
"... I just feel better on my 2004 Crown Vic, ...............if my truck did the same thing my life would be simpler...and I like things simpler..."
The problem is really Michelin. Had you gotten Goodyear, or whatever, they would have said 44 psi. I don't understand why Michelin is the only one that does this, but they are alone in this practice.
So rest your mind, the problem doesn't really exist.
A friend of mine was recently saying that he thought the Ford Five Hundred might make a better buy for him than the Honda Accord -- one of his rationales was that the Ford, with its 17" wheels would hold up better than the Honda, with its 16". (He drives a LOT -- around 60k mi/yr.)
Leaving aside the merits of each of those cars, is there any evidence that larger wheels have an effect on the car's durability?
I am not sure of the rational? With his 60k a year, depending on tire make and model selected, he would change tires (depending on actual mileage and his wear patterns on specific tires) easily once or twice a year.
Also it would seem to me, if he wished to maximize his wear and keep his costs low, to get the best tires consistent with long wear like an 80,000 mile guarantee type like GY Comfort Treads or Triple Treads. Even in that context it might be interesting to compare the price difference between the 15, 16, 17 in sizes. For sure my goal given his circumstances would be the best tire and also longest wearing with price performance thrown in.
If I did that kind of mileage a year, I would definitely look to getting a diesel. Actually I got a diesel I do app 30,000 miles on this car) and the 360 UTOQ GY LS-H oem 15 in tires (not sterling performers by any means) are projected to go 100-130k miles. So if I can project from my projections, the 15 in GY C/T or T/T with a 700/740 UTOQ (T-rated), or app 2x more would be projected to go app 200,000-260,000 miles.
Well, I have to say that I really like the Cross Terrain tires I put on my 2001 Tundra. Not only are they smooth (comfortable) tires, but they are easy to hide that a 4500 pound pickup is travelling 90 MPH!!! :P No, I don't normally drive like this, but I keep having to catch myself following some sporty vehicle that is bee-bopping along.
I enjoyed your thoughtful, informative post. I am quite interested in tires and seek to get the best rubber for my vehicles. Tire pressure is another topic that I follow carefully. I just purchased an Accutire pressure gauge at Sears and try to keep all my tires at the correct pressure because I think it is a crucial safety factor and controllable by me.
Your point about the cold tire pressure being altered by even a one mile trip to the gas station intrigued me. I test my tires after a night of sitting in the driveway and if they are low, I leave the caps off and drive to the gas station. I then typically fill the tires with two pounds more than the recommended pressure. My feeling is that this gives a firm ride and allows for a margin of error when over time the tires deflate.
What do you think of this stategy? I'd rather be two pounds over than two pounds under.
Your point about SUV's and their tendency to rollover is well taken. I purchased a Lexus RX300, an SUV, and felt that if I drove it carefully I would never have a rollover problem. While driving on I-95 I saw a Chevy Blazer try to enter the middle lane as another truck tried to occupy the same space coming from the left lane. The Blazer swerved to avoid the collision and rolled over into a ditch. This made me realize that I couldn't avoid rollovers with my SUV just by being careful. Extenuating circumstances could cause me to roll. I traded the Lexus in for a Subaru Outback Wagon, getting even better utility and a lower center of gravity.
Some seem to think that the large size of the SUV means safety. But one gives up so much accident avoidance capability in these things. My guess is that SUV's are a fashion statement and will soon go out of fashion. Wagons will return and provide the carrying capacity we need and give us a safer ride.
Again, I enjoy your posts. Keep on contributing to the discussion.
>You wrote: “Leaving aside the merits of each of those cars, is there any evidence that larger wheels have an effect on the car's durability?”
No, none that I know of or can imagine, either, for that matter (gearing addresses this issue, I’d think, and wheels/tires are just a part of the final drive gear ratio adapted for whatever size wheel is desired). If I understand correctly, I wonder what your friend must think of the durability of the original Mini -- with 10” rims! :-)
-Kauai
(Why are you all looking at me like that so expectantly? Two sentences. That’s all you get. No more. I can do it, too, you know? This is proof. All right, so “Good night,” then.) ;-)
>You wrote: “I enjoyed your thoughtful, informative post.”
Thank you. That’s very kind of you to say. :-)
>You wrote: “ and try to keep all my tires at the correct pressure because I think it is a crucial safety factor and controllable by me.”
I agree.
>You wrote: “Your point about the cold tire pressure being altered by even a one mile trip to the gas station intrigued me.”
At the point where the tire meets the road, the tire is “squished down.” The cords, belts, etc. in the tire are being flexed constantly as the tire rolls along creating lots of internal friction, which in turn generates heat, which heats the air in the enclosed volume of the tire, which raises the pressure. Rub your hands together vigorously the skin gets hot in a matter of mere seconds, doesn’t it? I think tires are much the same. The pressure increase will not be a lot for a short, slow-speed trip.
Don’t take my word for it. Check your tires before you drive off, and note the pressures. Check them again at your destination. See for yourself how your particular car and tires behave over a given distance, however short.
>You wrote: “I then typically fill the tires with two pounds more than the recommended pressure. My feeling is that this gives a firm ride and allows for a margin of error when over time the tires deflate.
What do you think of this stategy? I'd rather be two pounds over than two pounds under.”
I agree with your strategy, and I encourage everyone to do the same.
Higher tire pressures give me better steering response, better dry grip (up to a point), better hydroplaning resistance (with considerable pressure increase), lower rolling resistance with better fuel economy, greater resistance to dangerous heat build-up at speed, better protection for rim lips on pot-holed streets, and reduced tire wear. Did I miss anything?
These are all advantages, you may note. So, why don’t we all do this?
Rough ride. It can get rough depending on how much additional pressure you decide to run; try it, you’ll see. The higher you go with tire pressure, the more the whole suspension system beats you to death. Higher tire pressures help one to appreciate the shortcomings of the local “infrastructure!” ;-)
I would encourage everyone to keep the valve caps on the valve stems at all times. The valves need to be kept clean and dry lest they malfunction. If water is allowed entry, it can later freeze, expand, and possibly release air, or the ice can simply interfere with inflating the tire. It’s best to avoid any problems by keeping the caps on at all times.
>You wrote: “I purchased a Lexus RX300, an SUV, and felt that if I drove it carefully I would never have a rollover problem.”
I understand.
When I was young, I wanted to believe the same thing about riding motorcycles. If I rode with great care and attention, I thought I could mitigate the dangers, enough to make it reasonably safe. I was optimistic, as most young men are. It’s difficult to have a “small” accident on a bike. The rider is the bodywork; legs are “fenders,” etc. I don’t believe I ever spoke with a fellow motorcyclist who didn’t have scars and harrowing tales to tell. Eventually, that came to include me, too. I finally stopped riding motorcycles, and I would not resume riding despite the appeal of today’s bikes.
Enjoy your Subaru Outback. That WRX STi sure looks tempting
>Higher tire pressures give me better steering response, better dry grip (up to a point),
I agree with all these points in the whole message. Additional suggestions: depending on the kind of vehicle inflating front more than rear may improve steering without hurting ride. BUT try a few sharp swerves to see how the tires and the vehicle respond. Loading the vehicle with passengers or weight for a trip will change that feel also. Try a few evasive maneuvers to test your balance.
I adjust tires a little high at the gas station and then recheck the next morning with the car in the garage so the sun is not heating up the tires on one side.
I NEVER adjust tire pressure when below freezing without coming home and rechecking in the garage after the car has warmed above freezing. If a little water gets into the Shrader valve and freezes, it can open the valve causing a small leak until temp there rises above freezing. I had a tire go down one time in very cold weather and I think that's what happened. Releasing the air causes some condensation of the moisture in the air in the tire as it's released to a lower pressure environment; that moisture collected on the rubber seal.
I would modify your procedure (you are not wrong, but this is how I do it, which may work for you, I believe it works for me)...just prior to driving home, go to nearest air pump, hopefully within 2-3 miles of home...I overfill to 6-7 psi (remember, now the tires and air are hot) over the cold psi I want...example, my Crown Vic calls for 35 psi cold, per Ford, which would be 39 psi hot (just an estimate, add'l 4 psi not always exact), so I overfill to 42-44 psi and drive home...
Let sit overnight and check next AM before sun hits tires, so all tires are as close to "equal" as possible in their respective environments...let out pressure until all tires read 37-38 psi cold, and when they heat up all will be well...I do this once every 3-4 weeks (I have checked intermittently, and I now know that my Ford tires do NOT leak more than 1-2 psi per month, apparently good sealing tires...if they lost 1-2 psi weekly, like my former Prelude, I would undergo the overfill procedure weekly)...
I now have 2-3 psi over reco cold psi from Ford, slightly firmer ride, and can lose almost 4-5 psi before I am at 33 psi, 2 lbs less than reco, but certainly NOT unsafe in any way...
Once you respect tire pressure as the ONLY thing that keeps you on the road, it becomes a labor of love, even tho I sometimes laugh at myself, since I know folks who check their tire pressure every oil change instead of every month...how they don't have blowouts amazes me...
I did a quick search of previous discussions and couldn't see anything about this issue so I'm hoping somebody out there can help.
I bought a set of Goodyear tires (I drive a 1996 Escort) a while back and found that I cannot inflate them at the local gas station (any gas station actually) - I need to go to a proper garage anytime I need air, which is rather inconvenient. The dealer assures me that this is nothing extraordinary - something to the effect that valves being made these days all have this issue. But no one else I've talked to has ever heard of this.
Any advice/comments would be appreciated - I'd like to get the valves changed out for a start, but am unsure if this will help (if in fact all new valves have this problem).
I've found some filler hoses do not properly depress the valve stem. Are your valves shrader types, or do they look different? I bought my Nokian WRs just last fall, and I have no problems, other than the above.
Question to all those in the know including Connor and tire shops professionals
I'd like to upgrade Buick Rendezvous '04 CXL AWD from 16" 215mm to 18" rims with 235-245 wide rubber.
Purpose is to improve ride stability, reduce leaning at turns and improve performance on the snow/sand. As an added benefit also looking to get light rims 18.5-21lbs/wheel.
My current stock are very nice looking 8-spock wheels. I'd prefere something looking close to the stock and NO chrome. Pontiac Aztek/Buick Rendezvous share the platform.
I wonder if the problem is that the valves are just too short and don't stick out far enough so the filler neck fully engages the valve stem (what's inside the valve).
This makes the most sense from what the dealer said. To my knowledge there has not been any change in the valve standards (but that doesn't mean some off-shore outfit isn't making valves that don't meet the standard.)
I read the post and didn't realize it was you, Steve.
Some more insight:
If a tire, which bulges out in the area of the contact patch, encounters something the slices off the sidewall, the part taken off will be almost circular. This is particularly true of a tire that is running very low on inflation pressure. What I suspect is that the tire was low and during cornering, the road damaged the sidewall.
Hey Capriracer, I was just linking from Ask Connor - it was an interesting question.
But I haven't had a flat in almost a year now. :-)
Btw, Cudaal1, you'll need to post over there if you want Connor to see your question; he's pretty busy and doesn't get over here much. Over there being:
You might want to try to screw in a valve extender everytime you pump up the tire. The valve extender is cheap about $1. I have to use it on my car everytime I fill up the tire then take it off after I finished. My valve won't work with the portable home pump that I have. My other car works just fine with the pump. Good luck
Comments
The LTX M/S is like and 80/20 tire - 80% on road and 20% off road use. Depending on the type of vehicle they're installed on and the road conditions, you may or may not notice a difference in road noise. The LTX typically lasts longer, mileage wise (treadlife warranties notwithstanding).
link title
Click on "View detailed sizes..." for a PDF of the tire's specs.
Are we talking about the same tire????? "
No, but I was answering another post for a different web site!
My error in transposition!
I had a few too many windows open and was also doing some research on the CT and TT" that is: Goodyear Comfort Tread and Triple Tread, Passenger tires of course.
So for example the Michelin's listed on tirerack.com indicate max sidewall pressure for Michelin LTX for 275-70-15 S rated is 35 psi. Same size only H rated is 44 psi. On my Toyota Landcruiser (S R'd tires) it recommends 32 psi, so I run 35 psi and the most I ignore it is when it gets down to 32 psi. (given Michelin LTX S rated)
So for me there is a subtle adjustment with the new Bridgestone AT REVO's that have a max sidewall pressure of 44 psi (S R'd) I usually run it at 85% or 37/38 psi.
“ Dodge calls for 35 psi cold as standard tire pressure, and the Michelin LTXs state a max psi of 35, so we have a quandary ”
I don’t see a quandary, but perhaps there may be some misunderstanding on your part (or even possibly -- heaven forefend! -- on my part.) ;-)
>You wrote:
“ why would Dodge recommend a tire pressure that was the max psi on the tire they bought for the truck?”
Because they judged that this is the appropriate pressure for this tire on this vehicle. I doubt there is any conspiracy to be found here. It’s really quite straightforward.
Dodge specified a tire, and recommends running it at a pressure within that tire’s specifications. True, there’s no headroom for running higher pressures to alter the handling, for instance (albeit with harsher ride), but Hey! they gave you what works. Right?
Was it the cheapest solution? Probably. So, what’s new? ;-)
By the way, auto manufacturers tend to specify original tires that meet their needs, not yours. One of their greatest needs is to achieve better fuel economy ratings. Tires that yield the best fuel economy ratings tend to be very poor performing tires in most other respects. These tires are still reasonably safe, you understand, but they don’t provide the best grip, for example. Better grip means stickier rubber, and stickier rubber means greater rolling resistance, which, in turn, means lower fuel economy and so forth.
OEM tires are notorious for annoying just about all discriminating motorists. The automotive after-market is grateful for this. ;-)
Can you purchase a better tire than the OEM? Almost certainly. As ever, performance costs money. How much would you like to spend?
However, before you go down that road, you might wish to ask yourself what your goals are, and what you hope to gain by spending more. It is possible that the OEM tire actually gives you all you really need. I don’t know your needs, of course; just a thought.
For example, I’m sure everyone could benefit by fitting their cars with a max performance tire. But are their daily needs consistent with such a purchase? No, of course not, especially not when one considers the overall cost of such a tire -- summer only, short life, noisy, hard-riding, much more expensive, etc.
Now, me? Well, I just bought a set of max performance tires on lightweight wheels, but I’m not everyone and my needs and desires may, indeed do, differ from the majority. It was the right choice for me at this time. YMMV.
It’s all a compromise amongst many elements, and there is no “correct” answer, just answers that may better fit your particular needs, whatever those might be.
It’s your money, your car/truck, and your decision. Choose wisely.
>You wrote:
“ what would "Max Press 35 psi" mean to you?”
Why, just what it says, of course! Why would anyone think otherwise? The manufacturers aren’t trying to trick anyone here, for heavens sake. The legal liabilities of such “trickery” are frightening to contemplate!
It means just what they say: Don’t blow this balloon up beyond 35 psi, or you risk blowing up this balloon! It’s very simple.
So, when your tires are “cold” (see below for more on this), inflate them to 35 psi, and no more. Now you’re good to go. Fear not and enjoy your truck! :-)
Does this mean that this tire will blow off the rim, or explode at 36 psi? No, of course not. There is headroom built-in, not for least which reason is the need to accommodate the increase in pressure accompanying the increase in internal tire temperature as it rolls down the road under load -- friction creating heat, which warms the internal air, which expands as all gasses do when heated, and the pressure increases concomitantly. (Note, too, that tire pressure varies with ambient temperature. Thus, a ten degree F increase in ambient temperature will result in a one psi increase in tire pressure; a reduction in ambient temperature of ten degrees will reduce tire pressure by one psi, and so on. One psi change for every ten degrees F temperature change. This is an important safety issue when the seasons change, or in the high desert and similar climes. See below )
“Cold inflation pressure” is too often misunderstood. Sometimes it’s even misunderstood by the “experts” offering advice. (Present company excluded, of course! ;-) For instance, I suggest you go to the Tire Rack website (an excellent source for tires, by the way, and my choice) and while there, read their numerous technical articles on tires and wheels and such. The articles are generally good. However, note that their explanation of cold inflation pressure is flawed -- just flat wrong. They say “cold” means inflating in the morning before the heat of the day builds up.
No! That’s ridiculous! “Cold” means the current(!) temperatures you’re actually running in, not the freezing early morning temperatures! Geeze! What if you live in the high desert with its dramatic temperature swings between midnight and midday?!
Here’s my notion of a good definition of “cold inflation pressure”: The air inside the tire is at the same temperature as the air outside the tire, when the tire is in the environment in which one will be running.
How’s that? I like it; what do you guys think?
When is this the case? When the tires have been setting undriven for hours, probably four or more hours, and in the environment in which you plan to drive. (Not in your air-conditioned garage/workshop, for instance, but outside where it’s hot in the summer; or, colder in the winter!)
Even a slow drive in town for one mile will heat up the tires and yield a false “cold” inflation pressure. (Yes, this can be accounted for, but I’m trying to keep things as simple as possible here for the moment.)
Does the above make sense to you? It’s difficult trying to write posts that provide clarity.
How’m I doin’ so far? :-)
That’s not rhetorical, I’d appreciate some feedback from any of the readers here. I’m not here to be a know-it-all; I don’t come here to put people down. I’m trying to share my hard-earned knowledge with others so that they might be better informed. If I’m not doing well, you’d be doing me a great favor by helping me understand my shortcomings.
-Kauai (who asks for no more than a courteous “thank you” for his efforts, and who unfailingly thanks others for theirs.)
So to answer your question - "why would one interpret it any other way???" If you understand the engineering standards, then you can interpret it differently, but if you don't, then don't interpret it - follow it.
"why would Dodge..." From an engineering point of view, there isn't a conflict. The max is the max (don't forget that the actual load on the tire is probably not the max load). However, if you are questioning the engineering judgement of the guy that approved this, then you have to understand the engineering standards for tires - which leads us back into the circle of logic. Either you accept what is written on the sidewall as gospel, or you have to understand ALL the engineering behind the product - including reserve capacity, exceptions to the max pressure, etc.
Hope this helps.
Now, the Cross-Terrain SUV tires I got yesterday seem to be a little noisier, but this is in contradiction to what Michelin should be the case (they should be slightly more quiet). As such, I think a new set of LTX's probably would have been as loud or slightly louder than a new set of CT's.
So far I've got about 150-miles on them and they seem to be doing ok. I also need to follow/interpret the tire pressure according to Michelin since 'they' made the product.
Something else I do is always use my own tire pressure gauge as the final "standard" - I keep it in the glove box - and each vehicle I own has one. I watch my tires wear, and if I am over inflating (indicated by more wear in the centre of the tread) I reduce the pressure based on my gauge, and if under inflating (indicated by more wear on the outside of the tread, allowing for excess wear due to fast cornering and alignment errors - something that must be learned by experience) I increase the pressure, again based on my gauge. After a year or so I learn the correct inflation pressure for each vehicle and my use. Gauges can vary and the "correct" inflation pressure you use (not the max) can also vary slightly from the manufacturers recommendation.
Here in Alberta we see a large ambient temp variation (down to -50 C occasionally in winter, typically -20C and up to +40C in summer, typically 30C - and occasionally in spring it varies from -20C to +20C in a single day! It makes tire pressure control entertaining ;-) . Especially when you want to check the tires in the winter, chipping ice and snow out of the way, and trying to find a tire pressure station that hasn't frozen due to condensation in their hose!
The temperature swings within a 24-hour period in Alberta are just the sort of thing I was thinking of. Imagine on the day when the temperature varies from +20C to -20C that one sets the tire pressures at +20C. Then one finds oneself out driving about later at -20C. The temperature drop was accompanied by a very serious drop in tire pressure, arguably so low as to be deemed dangerous, and certainly not good for the tires. Clearly, that’s an extreme and probably doesn’t happen very often.
By the way, there are in fact tire pressure gauges that are more accurate and consistent than you may be accustomed to using. Autocrossers, road racers, etc. all require much greater precision in their gauges so that they might tune their handling reliably and consistently by adjusting tire pressure. However, they might be seen as too expensive for the average motorist; mine sells for $50, and it’s a big dial gauge bleed-down model too big to fit in my glove box with other items.
Another tool autocrossers require is an air tank, not a compressor, just a tank. I got mine at Wal-Mart for $18. I fill it up to 120 psi at our local village gas station and have my own air whenever I need it. I bought it when we got into autocrossing, where tire pressures are critically important and a 2-psi change can make a significant difference in a sport where positions may be won or lost by hundredths, if not thousandths, of a second. Drivers are forever adjusting tire pressures on the grid throughout the day, and an air tank is a necessary part of one’s toolkit.
Once I got this inexpensive air tank, I kicked myself for not getting one decades earlier. If you also have the luxury of a garage, it makes maintaining one’s tire pressures in the winter a breeze. For those who diligently maintain their tire pressures, an air tank is a must-have; if you buy one, you’ll be glad you got it.
Inflation pressure = load carrying capacity. So care must be taken that enough inflation pressure is in the tires to carry the load put on them. Otherwise the tire would get a fatique failure - not a good thing when it happens.
The second thing is that most vehicles will create different wear patterns in the front than in the rear - but the tire pressures are typically specified as the same front to rear (but not always). The vehicle manufacturer spec'd the springs, shocks, and sway bars based in the way the vehicle reacts with the specified inflation pressure. Changing the inflation pressure, especially the front to rear split, might cause some unanticipated handling issues, especially in emergency manuevers - just when you want the vehicle to behave predictably.
And last, but not least - The steering end of the vehicle typically causes the shoulders of the tire to wear faster than the center. Some incorrectly interpret this as too much inflation pressure. Typically, the rear tires wear in the center, which all gets balanced out if the tires are rotated regularly.
A good dose of caution and common sense goes a long way in this area.
Hope this helps.
So I do appreciate the discussion, for there are a fair amount of points! So I am of the variety that knows that I don't know enough. So if it triggers a type like that to do the required research, then that is a good thing!
But I think when it comes to T/P , the VAST majority might be classified under the "I have ignored it long enough" type category.
Are the OEM-supplied "flat kits" on high performance cars with no spare (M3, Mini, Corvette) any better than this?
I'll even go farther: There are some very good technical reasons to specify the maximum. For example: If the vehicle engineer, who is working 2 to 3 years before the vehicle is launched, is sizing tires, he would estimate the load on each tire. If his estimates resulted in a minimum of, say, 33 psi, then picking 35 psi would give him room for error. Plus using 35 psi makes the speed rating applicable as it is - no need to derate it. Knowing that many folks don't check their pressures, this is additional safety.
All this would be very important for a truck, which just might get loaded up with supplies from the garden center or the lumber yard - unlike a car which this scenario is very unlikely and where ride comfort is a very important consideration.
Plus going to a larger tire, with a lower inflation pressure, means more cost - and it's not just tire cost. Larger tires means larger wheels, wider fenders, beefier suspension, etc. All these things add up - so we may be talking about a couple of of hundred bucks to use what seems to be something unnecessary.
I hope this explains the situation.
(If you’re not up to this, please press the Page Down key, now. You’ll get past this eventually.) ;-)
>You wrote:
“I would certainly like to thank all of y'all who responded to my query, especially kauai who virtually composed a PhD thesis online...”
You’re welcome. This man will take that as a compliment. You’re a scholar and a gentleman, sir, and I thank you. :-)
>You wrote:
“ and let out air in the morning before the sun hits the truck ”
Aha! You’re thinking that the radiant energy from the sun will heat up the black tires on the sunny-side of your truck, increasing the pressure in those two tires, but not the offside tires, right? Now, if you adjust them so that they’re equal, left and right, they’ll be unequal after reaching operating temperature. I like the way you think; the details are important.
I checked that very phenomenon on one of our cars, and sure enough, the sunny-side tires were 1-psi higher than the shady-side tires after a short while in the direct sun, whereas they had been exactly equal in the garage shortly before. (You already knew I’d done that, didn’t you?) ;-)
I enjoy sharing my meager bit of “knowledge,” such as it is. :-)
>You wrote:
“ most of my past vehicles had reco psi of 30-32 psi cold ”
Yes; mine, too, although I have no experience with trucks, as we prefer sports/GT cars.
I wonder if, perhaps, the correct minimum everyday tire pressure for your truck might be 30-32 psi, or even less, with the large-volume tires? But, maybe, Daimler/Chrysler decided to instruct owners of this Dodge truck to run the max pressure all the time -- just to be on the safe side, for you and for them.
So Dodge might have recommended, say, 30-psi, along with recommendations of a 3-psi increase for load and higher speeds, while still leaving 2-psi headroom. Instead, they said “No. We don’t trust folks to maintain the tire pressures near the minimum safe levels, so we’re recommending the max, 35-psi, as the minimum.”
Just a bit of forgetfulness, coupled with normal air loss of maybe 1-psi per month, added to a 40 degree F drop in temperature and you’re easily 5-psi low, down to 25 psi (if you started at 30-psi about a month before.)
With only 25-psi in the tires, sudden evasive maneuvers could easily result in a rollover crash in a tippy truck or SUV. It happens all the time, unfortunately. Many folks are living on the edge -- teetering on the brink, so to speak -- and just don’t know it. One need only get that tall mass on an SUV or truck to swaying mightily, heaving to one side and then abruptly back to the other side, exactly as it happens in a violent evasive swerve to the left to avoid something, followed by an equally violent swerve back to the right (to stay on the road!), exacerbated by the likely oversteer slide that began with the first sudden braking/turning maneuver to the left (never brake hard and turn simultaneously if there’s any way to avoid it), and (the driver’s probably cooked by that point, but just doesn’t know it yet) that final pendulum swing back in the opposite-slide direction to the right, and ooopsie daisy -- over you go onto your head. You’ll be unhappy.
Instead, though, Dodge has recommended 35-psi for the minimum, everyday tire pressures, hoping to avoid the dangers of inadvertent low -- and dangerous -- tire pressures. This makes the ride harsher than would be absolutely necessary much of the time, but “ensures” that the tires are always at “nearer” maximum pressure to resist rollovers, carry extra loads, etc. No doubt, their likely mistrust of owners to maintain their tire pressures responsibly is a factor as well. They want to avoid any problems like the Ford/Firestone debacle (which was a tire pressure problem, not a tire problem, attributable to Ford foolishly recommending a normal tire pressure in the mid-to-upper twenties, as I recall. Softer ride, you know Now, they insist on around 35 psi, as I recall. Sound familiar?). If 35-psi means you Dodge owners ride around much of the time with harder-riding tires than absolutely necessary, well they don’t care. Can you blame them in this litigious society? ;-)
That might help to logically explain things. Is it right? I have no idea. I’m just speculating as I try to account for this rather odd business. I agree with you, you see; it’s not only odd, but it would leave me feeling the same unease that I sense you are experiencing.
I suspect that the relatively narrow-track, tall-and-tippy trucks and SUVs of today are actually hurt by modern, grippy tires. Today’s tires stick too well, generating g-forces unheard of in decades past. These higher g-forces probably contribute to rollovers. Tires from the past would just slide helplessly (which carries it’s own set of problems, obviously), rather than generate the g-forces sufficient to roll these vehicles over. And everyone seems to want big, wide, meaty tires, for that extra-aggressive look, giving yet greater grip, which is just what one doesn’t need in those tippy-mobiles. Unintended consequences, eh?
As I’m writing, it occurs to me that maybe Dodge deliberately selected the least grippy tire it could find, precisely to obviate the rollover dangers. Such a tire is one I would expect to see with an unusually low max pressure. Who knows?
You could try calling Chrysler corporation, but could you believe anything they said to you? Just another of Life’s Mysteries, I reckon. ;-)
I don’t know much about trucks, nor truck tires for that matter. However, from what I’ve read, the suggestion seems to be that much of what applies to car tires is also applicable to light truck tires. Apparently, many car tires can be used on trucks.
Please do correct me if I’m mistaken as I pursue my thoughts here. Some folks (to my everlasting amazement) would rather be wrong than be contradicted. Try to educate them, and they take offense. (That’s why I let many writers’ assertions, which are clearly false, just slide on by. I don’t need the aggravation of dealing with their “ungrateful” response. I prefer peace to combat, thank you.) They actively embrace ignorance. I’ve never understood that, but I suppose it’s part of the macho/BS, perpetually competitive, striving-for-ascendancy-in-the-pack, sort of thing. That’s not my way. Please tell me when I have it wrong -- I’ll be grateful, not angry and hostile.
Moving right along, then...
(You still awake?) ;-)
>You wrote:
“ so a tire with a max press of 35, 38, or 40 seemed logical, meaning that the tire was not inflated to its max pressure when inflated for the car on which it was installed...is it not odd to you that Dodge would reco 35 psi, but that they would call for a tire whose max was 35, leaving no leeway ”
Herein may lie a misunderstanding: Your words seem to carry the implicit assumption that load-carrying capacity increases with pressure up to the maximum permissible tire pressure.
That is a false assumption, albeit eminently reasonable, especially given the manner of displaying information on the tire sidewalls.
What is interesting, and a long-time puzzle for me until recently, is what is stated on the tire sidewalls. For instance, on the new tires I just bought, it reads: “Max. Load 1235 lbs. @ 51 psi Max. Press.” (I’ve omitted the metric data that’s also there.)
Strictly speaking, this statement is true. But, the assumption that 51-psi is necessary to achieve that load capacity is false. Yet, that’s exactly what most folks are likely to conclude with this “misleading” statement. This odd statement on the tire sidewall too readily permits misunderstanding, and if I were King, I’d order this practice changed. ;-)
My new tires are “Standard Load” tires (a.k.a. SL), and by international agreement in the auto industry, all SL tires shall reach their full load carrying capacity at 35-psi, regardless of whether they are also made stronger to tolerate even higher pressures safely.
(Do you see the glimmer of light ahead?) ;-)
There are two issues here: (1) Maximum load capacity, and (2) Maximum pressure. They are related only up to a point. Max load capacity is reached at 35-psi, and the extra pressure permitted (if available), allows the user, for example, to adjust the front/rear balance of grip, or give some added safety (I think) running at high speeds as it makes the tire less flexible, thus generating less internal heat, and internal heat is the enemy of tires.
From a FAQ on the Yokohama Tire website:
“A Standard Load tire may be branded with a maximum inflation of 44 psi, indicating the tire's ability to meet special performance requirements. It does NOT increase the tire's load capacity.”
Note, too, that there is also an “Extra Load” (XL) rated tire, which achieves max load capacity at 41-psi, again by international agreement. Most tires for autos seem to be SL rated.
Again from the Yokohama FAQ:
“Extra Load tires are limited by the load that can be carried with a maximum inflation pressure of 41 psi. An Extra Load tire will be branded with 'Extra Load', 'XL' or 'Reinforced' on the sidewall. A Standard Load tire does not bear any special identification.”
What they’re saying here is that an XL tire reaches it’s max load capacity at 41-psi, even though it may have a stronger design that permits even higher pressure capacity. Beyond 41-psi, an XL-rated tire does not increase the load capacity.
The 35-psi max pressure on your Dodge truck tires would suggest that they are SL tires, not XL tires, which are what I would have thought would be the more sensible choice for a light truck. Who would make an XL tire, but limit it to 35-psi? But, what do I know?
And, if indeed your tires are SL tires, additional pressure capacity would not yield any greater load carrying capacity, the max load capacity being reached at 35-psi.
“But, still ,” you’re probably thinking. Yeah, me, too. ;-)
Parenthetically, for those of my readers who still labor under the widely held misconception that the tire manufacturer determines the appropriate tire pressures front/rear on your particular car you may wish to read the following for your edification:
Again, from the Yokohama Tire FAQ on the web:
“The maximum pressure for a tire is always indicated on the sidewall. This maximum pressure should NOT be confused with the vehicle manufacturer's recommended tire pressure. The vehicle manufacturer information is listed on the Tire Information Placard located on the door post or glove box lip, and is also contained in the Owners Manual. ALWAYS follow the vehicle manufacturer's information.” [Yokohama’s capitals, not mine.]
At first glance, the notion that the tire maker knows their tires best, since they made them, after all, seems to make sense. However, this is irrational if you extend the reasoning. Consider: How many different year, make, and model of cars are roaming the planet? Never mind the additional complication of multiple tire choices on many of those models. Any given manufacturer’s tire might fit an awful lot of this myriad number of cars. Indeed, many different models of tire from, say, Bridgestone, would fit any given car. Who’s going to compile and keep current the necessary database of information for front and rear tire pressure for each and every one of those cars, and for each of the many models of Bridgestone tire that will fit? What happens when new models appear? Moreover, how do you propose they should squeeze all this advisory information onto the tire sidewall? The sheer volume of data is staggering. I really cannot see how the tire manufacturer can manage to squeeze all of that onto a tire sidewall. Can you? If so, you’ll have to tell me how. And how would I read it? Do you see the difficulty, folks?
The VEHICLE manufacturer designed the car and specified the tire. Between engineering computation, empirical testing, etc. THEY decided what pressures to recommend. The tires they selected as part of their design are part of the suspension system in a very real sense (sort of an air-spring). For the automotive engineers, tires are an integral part of the design of the car. They are not generally just an afterthought.
Although, having said that, there is the interesting case of our friend’s Dodge truck here, which may belie that assertion. Well
Note, too, that in his odd case, the max pressure is also the recommended regular running pressure. (That’s just a coincidence; don’t be mislead.)
What were they thinking at Daimler/Chrysler when they put together our friend’s truck? Probably a case of the Bean Counters over-riding Engineering, with Legal somehow left out of The Loop, else Legal would probably have blanched at the prospect of a marginal tire and commenced bleating loudly, foretelling catastrophe and doom But, what do I know?
Anyway, my friends, one should set tire pressures to what the CAR manufacturer recommends. It’s best to regard those pressures front/rear as a minimum. There are excellent reasons to exceed that minimum, though. For instance, on my P5 (recommended 32/32 F/R) I run 37/35 F/R as my regular pressures. The Dunlops on this car have a max pressure of 51-psi. It would be a mistake to run 51-psi in this car on the street.
My current tires (and recent tires) have a max inflation of 51-psi. Recommended pressures on our Si are 33/30 F/R, and on the Protege5 are 32/32 F/R for normal use. Both manufacturers recommend 3-psi higher for heavy loads or prolonged, higher interstate speeds. That still leaves an awful lot of headroom, far more than anyone would likely use in normal use. In fact, I’ve run 55-psi in the fronts on the Si when racing. This is hardly applicable to street driving, and running “even” 51-psi is wildly impractical and one is more likely to damage the tires at those rock-hard pressures than assist them. Not much “spring” left in the tire at 51-psi to absorb bumps and sharp things. Besides, 51-psi provides a ride quality on the street that quickly generates unhappiness.
Returning to the Dodge truck issue, and proceeding apace
>You wrote:
“ is it not odd to you ”
Yes, it is. And in the unlikely event I were to own a Dodge truck similarly equipped, I’d be unhappy. I’m just trying to help you see that what Dodge has done here is not necessarily “wrong.”
But it sure seems like they’re skirting the edge of “wrong-ness” here, doesn’t it? This may be taking cost-cutting measures a wee bit too far. I confess I’d want to replace those tires with something more to my liking.
And also, had Dodge recommended, say, 30-psi for your truck I’d have encouraged you to inflate them to the 35-psi max, and religiously keep them there for the rest of your life, checking them weekly and more often when temperatures change markedly.
>You wrote:
“does anyone see this, or am I just a bona-fide idiot???”
I see it, and “No,” you’re not. Again, I’m with you. ;-)
My tires are my lifeline, my connection to the road; as they go, so go I. After all is said and done with the drive-train and the suspension and the aerodynamics and it all comes down to what’s happening at those four small patches of rubber, the interface between the rubber and the road. I take my tires very seriously.
Driving your heavily loaded Dodge truck would leave me feeling I might be “pushing the envelope” at speed on those tires. I wouldn’t like that. ;-)
Well, Bob, (or is it Marsha? I’m confused.) I hope this has helped.
Feel free to ask further questions, and I’ll answer as best I can. Who knows? Chapter 3 might be forthcoming you never know your luck! ;-)
-Kauai (an old fart who hopes that, at the very least, he put a smile in someone’s day.)
Swerve, swerve, trip, roll?
Then we get into the question of whether SUV tires could be too grippy causing a trip.
Tire pressure monitors are coming soon. How much more expensive would it be to hook the tires up to a compressor for real time or periodic inflation adjustments (could you even do it real time with the pressures expanding from heat as you drive?).
How much does the inflation option cost in the HUMMER?
Steve, Host
Bob
It's standard on the H1 now. I think it was pricey, at least $1000, before, and the older iteration included goofy plastic adapters for the valve stems. The current version is more seamlessly integrated with the wheels.
2014 Malibu 2LT, 2015 Cruze 2LT,
Steve, Host
“ can one then attribute (partially) "curb tripping" to underinflated tires. Swerve, swerve, trip, roll?”
I’m uncertain what you mean by “curb tripping,” and I’m no expert, but of the interpretations that come to mind, I’d think, “Sure!” In fact, I’d think under-inflation is a major contributor.
It seems reasonable to me; don’t you think so, too?
>You wrote:
“Then we get into the question of whether SUV tires could be too grippy causing a trip.”
Yes, although I wonder if you’d agree with me if I shifted the emphasis a bit. I would suggest that the grippy tires are not at fault; rather the inherently unstable vehicle is at fault, while the grippy tires just exacerbate this problem. The SUV is the problem, not the tires.
It might be a good idea to refrain from putting, say, Potenza S-03 Pole Position tires on the typical SUV!
I imagine a “skilled” driver could force many of today’s SUVs to roll despite the tires being inflated to the maximum. Get that huge, tall mass to heaving about, and with the angles of lean that are generated, even a properly inflated tire will roll the shoulder under significantly which further exacerbates the lean and onto-the-roof-you-go.
I recall reading a piece in one of the auto magazines a number of years ago where the writer was describing his experience road testing an SUV. I don’t recall what the make and model was, but I don’t believe it was one of the ones that had a notorious reputation for rolling over. Anyway, the guy was running this SUV through the cones they set up as a reference standard for all their road tests.
Now, I think it’s fair to assume they had the car properly set up, with appropriate tire pressures, etc.
He rolled it onto his head! In “normal” driving while running it through either the sudden lane change test, or the slalom, I think. He was under control until he was suddenly on his head!
He was wearing a helmet, fortunately, and his seatbelts, of course. What I recall most was his description of how sore he was from the beating he took in the relatively low-speed rollover. He was clearly hurt.
When I was teaching my wife to negotiate the slalom in autocrossing, I recall I concocted this little ditty to help explain a point, and now I can add a bit for SUV drivers: [Sung in a sing-song manner with a metronomic cadence and swaying left to right.]
* * * * * * * * *
Left, right, left, right, dancing with the cones;
Left, right, left, right, onto the roof we GO!
Well, never mind
Lots of folks have suffered rollovers through no particular fault of their own. They’d maintained sensible tire pressures, etc., but evasive maneuvers alone put the thing on its head. These are inherently unstable vehicles. I would not drive one, much less own one.
But, I’m not looking for a fight with the folks who love their SUVs. I wouldn’t seek to deprive you of them. They’re just not for me, thanks.
And I try to steer clear of them whenever possible. ;-)
>You wrote:
“Tire pressure monitors are coming soon.”
Yes. They’ve been here for years, but now the government is requiring them on all new vehicles starting next year, I think? You can order them from the Tire Rack today, if you like.
I don’t know where tire pressure monitors saw their first use, but I recall first seeing them used on Indy cars some years back. Very useful for high-speed oval racing, where a tire can start to go down, but the centrifugal force of the rotating tire at 200 mph keeps the tire looking “normal” until it’s too late. I would think that suffering a tire failure on the wrong side of 200 mph would be very upsetting.
I seem to recall that Jaguar, I think, has this system in place on at least one of their sedans, and the Autoweek long-term testers were having problems with it. I could be mistaken.
I anticipate it will be a few years before these monitors become consistently reliable, and the consumer complaints die down. We’ll see
One of my concerns is that the states will commence checking on the functioning of these mandated monitors when they do the annual vehicle emissions testing, and we’ll be required to pay to repair the miserable things. It’ll probably cost a lot, removing a tire, or two, replacing the sensor/sender strapped to the center of the rim, remounting and balancing the wheel (probably damaging our nice alloy rims in the process), and we’re going to be furious.
The government is a bit too “helpful” for my taste. There are some kinds of “help” I can do without, you know?
Take care, folks, keep an eye on your tires, and, as AAA used to say, “Bring ‘em back alive!” :-)
-Kauai
“I am not young enough to know everything.”
-Oscar Wilde
I think it was a Jeep Liberty in AutoWeek. IIRC, the test driver did not walk away unscathed, either. I remember that the instability plus injury really turned me off to the Liberty.
***Jaguar, I think, has this system in place on at least one of their sedans, and the Autoweek long-term testers were having problems with it. I could be mistaken. ***
A Jag with electrical gremlins, can you imagine? :P
***states will commence checking on the functioning of these mandated monitors when they do the annual vehicle emissions testing, ***
I don't care much about the emissions testing, but wish all states had vehicle inspections. It's not required in my state, and I see tons of bald tires, burned out lights, and busted windshields, and the police never stop people for these offenses.
I would purchase an SUV, if it were responsive and fun, and included stability control. Something like an X3/X5 or M-class on the high end, but they're way out of my price range. I've driven a current model Yukon, and it was one of the blandest, most uninspiring things I've ever driven. Stability control should counteract a tire that is too grippy by braking the car if you're going too fast for a corner--allowing the enjoyment of a high-performance tire on an SUV while minimizing the risk of rollover that it might induce.
The funny part is they are wireless (of course), and Mazda warns if you are parked beside another RX-8, it can confuse the system as it will see all eight wheels. Not to worry, they say. It will regain its' composure as you drive away.
They increase the cost of "winter wheels", and most owners just use wheel/tire combos without the sensors and ignore the red light during winter.
The problem is really Michelin. Had you gotten Goodyear, or whatever, they would have said 44 psi. I don't understand why Michelin is the only one that does this, but they are alone in this practice.
So rest your mind, the problem doesn't really exist.
Leaving aside the merits of each of those cars, is there any evidence that larger wheels have an effect on the car's durability?
Thanks!
Also it would seem to me, if he wished to maximize his wear and keep his costs low, to get the best tires consistent with long wear like an 80,000 mile guarantee type like GY Comfort Treads or Triple Treads. Even in that context it might be interesting to compare the price difference between the 15, 16, 17 in sizes. For sure my goal given his circumstances would be the best tire and also longest wearing with price performance thrown in.
If I did that kind of mileage a year, I would definitely look to getting a diesel. Actually I got a diesel I do app 30,000 miles on this car) and the 360 UTOQ GY LS-H oem 15 in tires (not sterling performers by any means) are projected to go 100-130k miles. So if I can project from my projections, the 15 in GY C/T or T/T with a 700/740 UTOQ (T-rated), or app 2x more would be projected to go app 200,000-260,000 miles.
I enjoyed your thoughtful, informative post. I am quite interested in tires and seek to get the best rubber for my vehicles. Tire pressure is another topic that I follow carefully. I just purchased an Accutire pressure gauge at Sears and try to keep all my tires at the correct pressure because I think it is a crucial safety factor and controllable by me.
Your point about the cold tire pressure being altered by even a one mile trip to the gas station intrigued me. I test my tires after a night of sitting in the driveway and if they are low, I leave the caps off and drive to the gas station. I then typically fill the tires with two pounds more than the recommended pressure. My feeling is that this gives a firm ride and allows for a margin of error when over time the tires deflate.
What do you think of this stategy? I'd rather be two pounds over than two pounds under.
Bob
Some seem to think that the large size of the SUV means safety. But one gives up so much accident avoidance capability in these things. My guess is that SUV's are a fashion statement and will soon go out of fashion. Wagons will return and provide the carrying capacity we need and give us a safer ride.
Again, I enjoy your posts. Keep on contributing to the discussion.
Bob
“Leaving aside the merits of each of those cars, is there any evidence that larger wheels have an effect on the car's durability?”
No, none that I know of or can imagine, either, for that matter (gearing addresses this issue, I’d think, and wheels/tires are just a part of the final drive gear ratio adapted for whatever size wheel is desired). If I understand correctly, I wonder what your friend must think of the durability of the original Mini -- with 10” rims! :-)
-Kauai
(Why are you all looking at me like that so expectantly? Two sentences. That’s all you get. No more. I can do it, too, you know? This is proof. All right, so “Good night,” then.) ;-)
“I enjoyed your thoughtful, informative post.”
Thank you. That’s very kind of you to say. :-)
>You wrote:
“ and try to keep all my tires at the correct pressure because I think it is a crucial safety factor and controllable by me.”
I agree.
>You wrote:
“Your point about the cold tire pressure being altered by even a one mile trip to the gas station intrigued me.”
At the point where the tire meets the road, the tire is “squished down.” The cords, belts, etc. in the tire are being flexed constantly as the tire rolls along creating lots of internal friction, which in turn generates heat, which heats the air in the enclosed volume of the tire, which raises the pressure. Rub your hands together vigorously the skin gets hot in a matter of mere seconds, doesn’t it? I think tires are much the same. The pressure increase will not be a lot for a short, slow-speed trip.
Don’t take my word for it. Check your tires before you drive off, and note the pressures. Check them again at your destination. See for yourself how your particular car and tires behave over a given distance, however short.
>You wrote:
“I then typically fill the tires with two pounds more than the recommended pressure. My feeling is that this gives a firm ride and allows for a margin of error when over time the tires deflate.
What do you think of this stategy? I'd rather be two pounds over than two pounds under.”
I agree with your strategy, and I encourage everyone to do the same.
Higher tire pressures give me better steering response, better dry grip (up to a point), better hydroplaning resistance (with considerable pressure increase), lower rolling resistance with better fuel economy, greater resistance to dangerous heat build-up at speed, better protection for rim lips on pot-holed streets, and reduced tire wear. Did I miss anything?
These are all advantages, you may note. So, why don’t we all do this?
Rough ride. It can get rough depending on how much additional pressure you decide to run; try it, you’ll see. The higher you go with tire pressure, the more the whole suspension system beats you to death. Higher tire pressures help one to appreciate the shortcomings of the local “infrastructure!” ;-)
I would encourage everyone to keep the valve caps on the valve stems at all times. The valves need to be kept clean and dry lest they malfunction. If water is allowed entry, it can later freeze, expand, and possibly release air, or the ice can simply interfere with inflating the tire. It’s best to avoid any problems by keeping the caps on at all times.
>You wrote:
“I purchased a Lexus RX300, an SUV, and felt that if I drove it carefully I would never have a rollover problem.”
I understand.
When I was young, I wanted to believe the same thing about riding motorcycles. If I rode with great care and attention, I thought I could mitigate the dangers, enough to make it reasonably safe. I was optimistic, as most young men are. It’s difficult to have a “small” accident on a bike. The rider is the bodywork; legs are “fenders,” etc. I don’t believe I ever spoke with a fellow motorcyclist who didn’t have scars and harrowing tales to tell. Eventually, that came to include me, too. I finally stopped riding motorcycles, and I would not resume riding despite the appeal of today’s bikes.
Enjoy your Subaru Outback. That WRX STi sure looks tempting
I agree with all these points in the whole message. Additional suggestions: depending on the kind of vehicle inflating front more than rear may improve steering without hurting ride. BUT try a few sharp swerves to see how the tires and the vehicle respond. Loading the vehicle with passengers or weight for a trip will change that feel also. Try a few evasive maneuvers to test your balance.
I adjust tires a little high at the gas station and then recheck the next morning with the car in the garage so the sun is not heating up the tires on one side.
I NEVER adjust tire pressure when below freezing without coming home and rechecking in the garage after the car has warmed above freezing. If a little water gets into the Shrader valve and freezes, it can open the valve causing a small leak until temp there rises above freezing. I had a tire go down one time in very cold weather and I think that's what happened. Releasing the air causes some condensation of the moisture in the air in the tire as it's released to a lower pressure environment; that moisture collected on the rubber seal.
2014 Malibu 2LT, 2015 Cruze 2LT,
Let sit overnight and check next AM before sun hits tires, so all tires are as close to "equal" as possible in their respective environments...let out pressure until all tires read 37-38 psi cold, and when they heat up all will be well...I do this once every 3-4 weeks (I have checked intermittently, and I now know that my Ford tires do NOT leak more than 1-2 psi per month, apparently good sealing tires...if they lost 1-2 psi weekly, like my former Prelude, I would undergo the overfill procedure weekly)...
I now have 2-3 psi over reco cold psi from Ford, slightly firmer ride, and can lose almost 4-5 psi before I am at 33 psi, 2 lbs less than reco, but certainly NOT unsafe in any way...
Once you respect tire pressure as the ONLY thing that keeps you on the road, it becomes a labor of love, even tho I sometimes laugh at myself, since I know folks who check their tire pressure every oil change instead of every month...how they don't have blowouts amazes me...
If you do have a blowout, this post by Connor may explain why it happened:
connortirerack, "Ask Connor at The Tire Rack" #849, 3 May 2005 5:51 pm
Steve, Host
I did a quick search of previous discussions and couldn't see anything about this issue so I'm hoping somebody out there can help.
I bought a set of Goodyear tires (I drive a 1996 Escort) a while back and found that I cannot inflate them at the local gas station (any gas station actually) - I need to go to a proper garage anytime I need air, which is rather inconvenient. The dealer assures me that this is nothing extraordinary - something to the effect that valves being made these days all have this issue. But no one else I've talked to has ever heard of this.
Any advice/comments would be appreciated - I'd like to get the valves changed out for a start, but am unsure if this will help (if in fact all new valves have this problem).
Cheers, and TIA
I'd like to upgrade Buick Rendezvous '04 CXL AWD from 16" 215mm to
18" rims with 235-245 wide rubber.
Purpose is to improve ride stability, reduce leaning at turns and improve performance on the snow/sand. As an added benefit also looking to get light rims
18.5-21lbs/wheel.
My current stock are very nice looking 8-spock wheels. I'd prefere something looking close to the stock and NO chrome.
Pontiac Aztek/Buick Rendezvous share the platform.
Any good advise is greatly appreciated.
This makes the most sense from what the dealer said. To my knowledge there has not been any change in the valve standards (but that doesn't mean some off-shore outfit isn't making valves that don't meet the standard.)
Hope this helps.
Some more insight:
If a tire, which bulges out in the area of the contact patch, encounters something the slices off the sidewall, the part taken off will be almost circular. This is particularly true of a tire that is running very low on inflation pressure. What I suspect is that the tire was low and during cornering, the road damaged the sidewall.
Hope this helps.
But I haven't had a flat in almost a year now. :-)
Btw, Cudaal1, you'll need to post over there if you want Connor to see your question; he's pretty busy and doesn't get over here much. Over there being:
Ask Connor at The Tire Rack
Steve, Host
Isn't that what you want in sand?
tidester, host
Sounds like the best course is to get the valves switched out at any rate.
Cheers,