Tire Help, Please

dlamastr · August 1998

Can someone please explain tire "codes" in plain
English? Specifically, what does "LT235/85R16E AT
BSW" mean? What's the difference between "BSW" and
"OWL"? How do I know what is best for me?
There's 6 different options on the Ford Super Duty
I'm configuring, and I don't know which one to
pick.

stanford · August 1998

No problem. The one you specified:

LT - Light Truck
235 - Tread is nominally 235 millimeters wide
85 - Tire height is 85% of width (200mm/side)
R - Radial (just about all tires are radial)
16 - Requires a wheel 16" in diameter
E - Load range E (usually indicates 10 plys)

BSW - Black side wall
OWL - Outline white letters

AS - All season
AT - All terrain

As for the truck, are you getting 6 wheels or 4? 2WD or 4WD? I'm ordering a 4x4 DRW and am getting the LT235/85R16 AT (all terrain) BSW tires myself.

I'd take the all terrains offered rather than the highway only tires if you ever expect to drive through even slightly muddy grass. The AT tires offered as factory equipment are generally very mild; they won't dramatically increase road noise and decrease comfort the way some models do.

Beyond that, wider tires will generally give better dry traction. Narrower tires will give slightly better mileage and may offer better traction on some forms of off-road tracks. Folk generally seem to think that wider tires also look 'cooler'. I will say that the SD has some mighty big wheelwells to fill.

dlamastr · August 1998

Thanks, stanford, for the info. I'm getting a 4WD SRW. The choices are much clearer now: I don't want white lettering, and I definitely want all-terrains, so it's just a choice between the 235/85 (narrow) and 265/75 (wide) tires, a difference of just under 1.25". What a difference in price, though: $170 MSRP. But, I guess on a $30K truck, it's a nit.

stanford · August 1998

Personally, I'd go for the 265s. They're only going to be load range D (8 ply), but the 235s look a little funny on that truck IMO. If you have a brochure handy, the tan SRW regular cab
on the accessories page has the 265s.. they're
a nice size. You probably won't see any large
difference between the two IRL.

The profile differences (85/75) mean that both
tires are almost the same height (actually a 2
millimeter difference) so gearing won't change
on them. Enjoy the truck!

KCRam · August 1998

Stanford,

All correct with one exception. The "235" figure is in millimeters, but it's the section width of the tire from sidewall to sidewall - this does include unloaded bulge width. Tread width is a bit narrower than section width, depending on the tire brand.

Also, the 265/75s on the Super Duty are E-range (10 ply) and have a higher load rating (3415 vs 3042) per tire than the 235/85E.

cdean · August 1998

I'd like to know what everyone else uses for their truck tires. I've had good luck with Bridgestones, and i've seen some bad Goodyears, and i wouldn't buy Goodyear. any comments?

KCRam · August 1998

from a recommendation by one of the guys in my Ram club, I dropped the OEM Badyears for Cooper Discoverer LT - deep all-terrain tread (a full 18/32s), some whine at speed, but tolerable, almost no weights to speak of to balance, and excellent wear.

I have them in the OEM size, LT215/85R16E, only $110 a throw at my neighborhood Cooper dealer.

stevek · August 1998

I got 265/75R16 Michelin X tires last year for my '97 with highway treads. It was on sale at Sears and paid $425.00 (thats right!!!) including mounting and balancing. You do not need new valves since they have a metal stem.

richflynn · August 1998

stevek,
I've done similar things with Sears for tires. BTW, if you go get a legitimate bid from any tie store, Sears will match it. The big advantage is that Sears has service points all over the US.

I had the Michelin high pressure tires on my '86. Good mileage, harsh ride. I originally had Firestones on my '92, slippery in the wet. Changed to Goodyear Wranglers. Damn things, only got about 65,000 miles out of them. I've got the Firestones on the '99. They are so new that none of the local stores had the inflation chart for the tires. I had to call Akron to get the correct numbers. (LT 265x75 16R all season) These seem better than the previous 'stones in the wet. We'll see.....

Rich

Brutus · August 1998

I replaced tires on my 92 F-250 at 40,000 and at 80,000. I could have ran them longer. They weren't bald, but the tread wears down to the point that they slip to much on wet surfaces since the truck has no weight in the back. When I put my truck in 4wd to stop from slipping in the rain, I figure it's time to get new tires. I like lots of traction. The first set I had were the stock 235 Firestone A/T. The second set were 265 Goodyear Wrangler A/T. The last set I put on in December were 285 BF Goodrich A/T. I only put about 7,500 miles on them before I sold the truck a few weeks ago. I suspect I would have replaced them after 40,000 miles like the other sets.

As far as size goes, I noticed a definite difference in mpg and the extra power required to move the truck with the 285s. I liked sitting up higher and the tires filled out the wheel wells better, but I think the 265s were probably the size I liked best of the three. The 235s got the better mpg and were probably the best choice on paper, but they looked pretty skinny on the truck. I'll be getting the 235 A/T tires on my new Superduty, but I won't have the same problem filling out the wheel wells. The new truck will be a 4wd dually. The 235s are the biggest tire available. What brand are the dually tires on the new truck? I think I heard that they were not the Firestones like the SRW tires.

KCRam · August 1998

Car and Driver tested a DRW F350 a month or so ago (issuewise) - it had General Grabber 235/85s on it. You will find yourself removing them in a hell of a hurry if that's what you get. Both my Fords (90 and 93 F150s) had General Grabbers as OEM, and they sucked like a ShopVac. Wore out like cheap doormats. The 90 I only had for 2 years, so I wasn't concerned much, but on the 93, I swapped to Wrangler RT/S of the same size, and they still had plenty of tread after 45,000 miles of use.

daveperc · August 1998

Brutus,
Couldn't tell by the entry. Did the mileage difference come from error in odometer reading from different size tires? The larger tire diameter would show up as less miles, giving you the impression of lower mileage.

Brutus · August 1998

That may have been some of it, but I'm sure I actually was using more gas. When I first put the 285s on in December, I know I had to push the gas pedal down a little harder to move the truck. I didn't notice it when I went from the 235s to the 265s. The 285s are just big tires. It takes more to turn them. Of course, the 5.8L had plenty of power to do the job.

I have to laugh at the guys who have these compact pickups with lift kits and huge tires, but they haven't done anything to the engine. Heck, they'd probably get stuck in a mud puddle. They create all this clearance and they put on tires with lots of traction, but the engine probably is working close to max just to push the truck on pavement. Put them in some mud, and they will be very lucky if they can get those tires moving.

cdean · August 1998

unless they have enough sense to change the differential.

pttaylor · August 1998

Does anyone know what the maxamim tire size I can put on my 15x7 stock Dakota rims? I currently have 215R75/15s that were original equipment. I would like to go to a wider tire. Thank all of you for your helpful info throughout the Pick-up forum!-PTTaylor

stanford · August 1998

You could fit around a 265/75R15 without too much trouble. You might be able to get a 285/75 but that would be a very big tire for the 7" wheel (I had them for a while on my Ford).

Make sure that you have enough clearance when turning that the tire doesn't hit the sway bar and/or inner fender wells also. If you use an aftermarket tire with more backspacing than stock this will be less of an issue.

Brutus · August 1998

Just remember that, just because it fits in the wheel well without rubbing anything when you hit bumps and turn in regular driving conditions, it doesn't mean it is the best tire for the truck. You could still be limiting your ability to drive off-road or even on dirt side roads that have deep ruts. The looks of a vehicle are obviously important, but it's a good idea to make sure that the loss of functionability (I think I just made up a word) is a trade-off you can live with.

amadeus131 · September 1998

I'm still trying to piece together my dream S-10 4WD ext. cab pickup. (It's looking more and more like I'll have to order a '99, since all the '98s I see on the lots are pretty stripped.) I'll be getting the 4-speed automatic and probably the "regular" Vortec V-6 (as opposed to the high-output one). This will be a "city truck"; I drive about 20000 miles per year, but I won't be hauling more than an occasional light load. I just want the V-6 engine and 4WD capability for the upstate NY winter. I should add that I seem to attract nails and go through tires like Kleenex. (I already lost one of my Sunfire's "upgraded" tires at 31000 miles while on the Ohio Turnpike; I nearly lost another 2500 miles later, but saw the nail in time to have the tire patched.) With this kind of configuration, I have only one choice of 15" aluminum wheels, which makes things easier. The tires that would come with them are P235/70R15 all-season SBR BSW's. Will these suffice for my non-off-roading lifestyle? Or if they're kind of weak, is there anything marginally tougher, that would still not be overkill or ruin my mileage? I mean, it would be a sin for a guy like me to get the ZR2 package. I bet THAT'S expensive if you pick up a nail.

pttaylor · September 1998

In a post I submitted on august 21, I incorrectly said that I had 15x7 inch factory rims. I was mistaken. They are 15x6. My new question is "Can I put up to a 235R75/15 tire on my '98 Dakota 4x2 using the factory 15x6 inch rims????
Another strange occurance is that I have just turned 8600 miles on the truck and the factory Goodyear Invicta 215R75/15 tires are worn out! I had them rotated at 3500 miles (fronts were wearing badly then) with oil change. The tires are wearing badly on both outer tread shoulders with a "cupping" effect! Is it out of alignment and/or camber problem? Warranty should hopefully fix this I think with only 8600 miles on this truck? Any thoughts on this? -PT Taylor

stanford · September 1998

I'd guess that 235/75R15s should be fine on a 15X6 but have never personally run that combination. Your best bet is to check with your local NTB or Discount Tire store.

cdean · September 1998

I ran 235/75R15s on a 15X6, it works.

stevek · September 1998

to pttaylor:
Use 235 tires (I prefer michelins). If both outside edges on your tire wears it means you had them under inflated. If it gets "cupped" it means that your alignment is off. When you get the new tires have the truck aligned as well and keep an eye on the tire preassure.

Mac15 · September 1998

If you live in or have to do a lot of mountain driving it can also cause your tires to wear like that.

pttaylor · October 1998

You'll never guess what the service manager did for me!!! I took my 1998 Dakota with the worn out 8600 mile tires and he upgraded me from those hidious 215/75 Goodyear Invictas to 235/15 Wrangler RS whatevers. He told me that the front end was out of alignment, most likely since the day I took delivery. He upgraded me at no cost whatsoever!!! I all most fell over!!! The truck handles great and no noticable mpg increase!
After a Horrible experience with a 1996 KIA (Kept In Arbitration) Sportage with front-end trouble, this was nice thing for that service manager too do for me!!! -PT Taylor

bdon · November 1998

I need some help understanding how flotation measurements compare with metric measurements on tires. For example, how does a 31x10.50R15 compare with a 255/70R16? I'm looking at the '99 Silverado with factory tires of 255/70R16. But my dad has a '96 Silverado with 31x10.50R15's which look really nice. What's the difference?

hawkpilot · November 1998

Ok, I'll give it a shot...

The first number is the nominal width in mm. I think this is taken where the tread meets the sidewall (anyone feel free to correct me here, this is from memory!) The second number is the "aspect ratio" which is the height (above the rim?) over the width, in percent. The letter R is for "radial", and the final number is rim diameter in inches(!). To find the height of the tire in your example,
((255 x 0.7 / 25.4) x 2) + 16 = 30"
and the width is just 255 / 25.4 = 10"

so the tire could be classified as 30x10R16

HP

KCRam · November 1998

almost got it, hawk

The width is measured from sidewall to sidewall at its widest point in an unloaded state (loaded tires have some additional "bulge" width).

bdon,

The physical size equivalent for a 31x10.50R15 would be a 265/75R16, if Chevy still offers it.

hawkpilot · November 1998

Thanks for the correction!

HP

bdon · November 1998

Thanks to both of you for the feedback. That's helpful. But why then would a company manufacture both a 31x10.50R15 AND a 265/75R16?

http://www.michelin.com/us/eng/tire/catalog/ltxms.htm

Michelin apparently makes them both? Does that make any sense?

stanford · November 1998

Well, for one thing they have different inner diameters. Is that enough of a reason?

KCRam · November 1998

Flotation tires are normally intended for off-road use, the LT-metrics are usually intended for highway or on/off-road combinations. There are different tire construction issues involved - usually a flotation tire has a stronger sidewall so it can be aired down for off-roading.

KCRam · November 1998

no, you will need the 16x8s. The 16x6.5s will not hold them at all.

dave40 · November 1998

I know 285s won't fit on 16/6.5s wheels I want to know if 285s will fit in the wheel wells are they to wide ? I will have fenderflares on my new SEIRRA 2500 How will the truck handle compared to the stock 245s ?

cdean · November 1998

I will be taking a 4x4 double cab SRW with
Bridgestone M/Ts to Colorado from Texas in January.
Need some advice on the winter driving in the mountains. Will I need a different tire, or do i need to get chains, both? Common sense tells me the mudder tires will not be good in snow. I know nothing of driving in Colorado in the winter, so any info isappreciated.

KCRam · November 1998

285s should fit under the wheelwells. You're talking less than an inch wider on each side than a 245, so unless your 245s are right at the edge of the flares, you should be fine.

KCRam · December 1998

if your speedometer is accurate with the stock 245s, the actual speed will be about 4.5% higher. An indicated 55mph will actually be 57.5mph

dave40 · December 1998

Thanks KCRAM I will send you all the money I save on speeding tickets!

cym · December 1998

I am trying to decide between the stock tires on a new 4X4 Toyota Tacoma (Styled steel wheels 15X6") or an upgrade to the Aluminum alloy wheels, 15X7". Are there any advantages (or disadvantages) to aluminum wheels over the long term or would it be just a matter of looks?

stevek · December 1998

When I replaced the steel rims with aluminum on my S10 Blazer it handled and rode better. I don't know if it was my imagination or not, used the same tires.

KCRam · December 1998

steve,

There could be one of three things improving your ride:

1 - proper balancing - your tires may have become unbalanced on the old steel rims
2 - reduced weight - the aluminums generally weigh less than steel, and may change your ride and handling
3 - bad steel wheel - it could have been out-of-round or bent from a pothole

tjosh · January 1999

Speaking of tires, the last time Consumer Reports rated truck tires (jan 96, I think), they concluded that the Dunlop Radial Rovers were far and away the best "all-around" tires (good wet & dry traction, acceptable braking, good handling, nice ride, & only $85-90 a pop). Has anyone used
these? I've used Dunlops on my car (haven't bought a pickup yet . . . ;-) ), & they seem to be great tires . . .

Davydd · January 1999

Automobile magazine's "4x4 Field Guide" special magazine issue that can be found on newsstands has an article titled "Tires for Trucks" that tests 8 different AT tires. The tests were conducted on a Jeep Cherokee. They tested them extensively on-road and off-road for noise, comfort, handling, braking and lateral acceleration.

div2 · February 1999

I have had good results with the Dunlop Sport Rover GTX; they lasted over 46,000 miles on my 1993 Pathfinder SE. I switched to the Pirelli Scorpion A/T because I needed increased snow traction. I keep an eye on the tire pressure, check the front end alignment every 15K, and rotate the tires every 5K.

markbuck · February 1999

Goodyear (the only big american tire maker left) has a good website for rolling diameters, what tires require what rim width, etc.

akjbmw · February 1999

See Tire Tech under Tires in the left vertical bar at The Tire Rack. http://www.tirerack.com/. They do provide information and tires for light trucks.

Or try National Tire & Wheel at http://www.natltire.com/. If its there, I didnt find technical explanations, but they had some serious off-road stuff.

willvlv · February 1999

I just bought a new Dodge Ram SLT 3500 4x4 long-bed, dual-rear wheel, diesel. It's an awsome looking truck, except it came with puny little tires that don't match the character of the rest of the truck. It's like a backpacker wearing penny loafers. Anyway, if you have are aware of the largest AT tires that will fit on the stock wheels, or know of a good wheel/tire combination, let me know. I'm thinking about putting some B.F.
Goodrich LT235/85R16's all Terraines on it?

stanford · February 1999

How wide are the wheels, with what offset? You really want to watch the rear wheels to make sure there's no rubbing or heat buildup when loaded.

willvlv · February 1999

If I keep the OEM stock wheels on it, which I hope to do, they are 6 inch wheels. What do you mean by rubbing and heat build up? Do you mean
rubbing on the fender wells? ...or what?

Thanks for your feedback.

tnt2 · February 1999

I think stanford is talking about the duals rubbing together when loaded. One other thing to look at is the load range of the tire and that required of your truck. I think the BFG's fall in the "C" load range. Most duallies with diesels recommend an "E" or at least a "D" load range to handle the weight. My F350 also requires 65psi in the front tires. Isn't the max on the BFG's 45? (referring to AT's) Also I think your wheels are a little narrow for those tires.

stanford · February 1999

I thought that the Ford DRW wheels were 6 1/2"? And this year didn't they have more offset (allowing the 235s as factory for the first time)? I may be wrong though. The 235/85R16s were factory on my '93 SRW with 7" rims.

tnt2 · February 1999

They could be 6.5", never really checked. My older duallys were all 6", which seems to the standard for aftermarket rims. There is a good amount of space between them though. Saw a set of Perrelli desert dogs today, might try 'em when the time comes, about 2 months. Has anybody had any experience with them?

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