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Will Narrower Tires With Taller Sidewalls Return, To Improve Fuel Economy?
hpmctorque
Member Posts: 4,600
Put another way, will the drive to improve fuel economy stop, or even reverse, the trend of the past several years, to larger wheel diameters, coupled with wider, lower aspect tires? I wouldn't be surprised if it did, as wheel and tire shapes and sizes have changed to meet changing needs over the decades.
Do you have any thoughts on this?
Do you have any thoughts on this?
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Comments
And the truth is, cars don't have to get much smaller. Only engines do.
Family sedans don't need 300 hp to get the kids to school and mom to Wal Mart. The ability to go 0-60 in 5.9 seconds doesn't make rush hour traffic move any faster.
Families can still enjoy enough interior volume for comfort. They just can't have all that, and high performance, too.
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As for weight, according to some specs I found on www.tirerack.com, it looks like the bigger tire weighs around 37-38 lb, compared to around 30 for the smaller.
I really didn't see a noticeable difference in fuel economy with this change, but it could just be the type of vehicle. For instance, my truck only has a 3-speed automatic, and is pretty torquey, so it really doesn't have to do a lot of shifting. But on a more modern vehicle with a lot of gears and less torque, putting on bigger, heavier tires that cause more friction and end up making the overall ratio fairly taller just might make the car rely more on the lower gears in some situations, which could use more fuel. But on the flip side, perhaps going to a smaller, lighter tire on that same car would make it rely a bit less on the lower gears, saving a bit of fuel?
Similarly you could get mpg gains by making lighter vehicles? Would we strip structural strength and airbag systems, to make a lighter vehicle to get better mpg?
I don't think so as the gain in mpg is minimal compared to the public problem of reducing safety.
You could also if people wouldn't get sticky soft rubber snowtires, just so they could get better mpg with their All-season tires.
Aside from the gains in mileage and unsprung weight I'm of the firm belief that cars with skinny tires were more fun to drive, at least if they were RWD cuz you didn't need much power to get the back to rotate and oversteer through corners. :shades:
2001 BMW 330ci/E46, 2008 BMW 335i conv/E93
Hey, ties and lapels alternate between narrower and wider, so why not tires? Well, okay, ties and lapels are pure style statements, whereas tires are functional. There's an important style element in wheels and tires too, of course, judging by what people pay for upgrades and after market ones.
Maybe the discussion title would be a bit clearer if it said narrow tires and "taller" sidewalls? Or maybe it's a regional speech thing, like Coke or pop, cart or buggy?
02 explorer 245-70-16
04 escape 235-70-16
07 fusion 225-50-17
the mustang was considered to have larger than average tires when it was new.
tread design and tire composition also affects mileage.
So do tire pressures. Recommended pressures on hybrids are typically high. Tire makers and car makers may start to build tires designed to run higher pressures to improve mileage. Suspensions would be re tuned for these higher pressure levels.
2001 BMW 330ci/E46, 2008 BMW 335i conv/E93
It would be interesting to know how much mileage would improve if tires could be inflated to 50 psi, or 60, say.
High gasoline prices are shifting the priorities of many motorists to better fuel economy. It would seem logical, then, that tires for the more economy oriented vehicles, if not most vehicles, will be reconfigured to conform to the desire for higher fuel economy. Since narrower tire widths and taller sidewalls, plus higher tire pressure help fuel economy, that's what you'll begin to see. I think it's a simple matter of shifting priorities.
Yeah, sure, once more people wake up to the negative effect these wheels have on fuel economy, the demand for them will decrease. What's cool today is out of style tomorrow, and blingy wheels are primarily a fashion statement. Now I wouldn't try to predict just when this will happen, or to what extent, because people are fickle, but its probable we'll see changes wheel and tire changes associated with fuel economy becoming a higher priority.
Think of ties and suit lapels; narrow gives way to wide, then, at some point, narrow, or at least narrower, becomes fashionable again. Now neck ties and lapels are pure fashion statements, whereas wheels and tires have an important functional component, in addition to style and fashion, so these differences have to be factored into the fashion cycle analogies. Also, many men have abandoned suits and ties for a less formal look. By contrast, last time I looked, you can't do without wheels and tires when you drive.
I am not sure what taller sidewalls have to do with it - perhaps they will also need to get taller so that the visual effect of big rims and tires will be maintained? I do know this - it is not likely that automakers will begin to specify 50-60 psi unless tire construction improves a lot, because pressures like that give a very hard ride in most cars, even ones designed for a soft ride.
What someone said above resonates with me: cars will need to be designed slower to save gas, no-one needs to go 0-60 in 6 seconds in their grocery getter. And WHEN cars are slower, the massive tires they have on them now won't be necessary any more. Which is nice, because low profile and ever larger-diameter tires are so expensive to replace, and needlessly so on the family car.
2014 Mini Cooper (stick shift of course), 2016 Camry hybrid, 2009 Outback Sport 5-spd (keeping the stick alive)
Ain't that the truth! I can even tell the difference with my Intrepid when I raise the pressure from around 35 psi to 40! I'm sure 50-60 psi would make for a real bone-shaker.
Just as a reference point on the increasing size of tires, my 2000 Intrepid has 225/60/R16's, while the 2008 Charger has 215/65/R17's as the base tire. Interesting, in this case they actually started trending to a slightly narrower, taller tire.
As for pricing, the cheapest Intrepid tire on Tirerack.com was $62. For the Charger, it was $73.
The base Intrepids used to come with something like a 205/70/R15 tire...it was 2000 that they upgraded the base model to the 225/60/R16. I wonder, if I found a set of those 15" wheels and put the narrower tires on, if I'd see a noticeable change in fuel economy? That's about 9% less tread width to cause friction, and the smaller rims would probably shed a few pounds of rolling weight (or whatever the technical term is) from each wheel.
I am not sure what taller sidewalls have to do with it - perhaps they will also need to get taller so that the visual effect of big rims and tires will be maintained?
The sidewalls themselves wouldn't have to get taller. However, since the sidewall measurement is always listed as a percentage of the tread width, then as you make the tread narrower, they'll have to make the aspect ratio taller for the tire to have the same diameter. For instance, if you drop down one size, say, from a 225/60 tire, to keep roughly the same diameter you'd have to go to a 215/65.
While it's true that the aspect ratio has no bearing on fuel mileage, tire pressures do.
As previously mentioned higher pressures would mean a punishing ride unless the sidewalls get taller. Again look at the 65 section tires fitted to the current Prius (rec pressures are 40/42 PSI), those are quite tall by modern standards.
2001 BMW 330ci/E46, 2008 BMW 335i conv/E93
Actually, if you change the aspect ratio, isn't that somewhat like changing the car's axle/differential ratio? For instance, if you fit a really small tire on the car that reduces the circumference by 10%, wouldn't that be the same as fitting a shorter (numerically higher) axle ratio? The smaller tire is going to make it rev faster at any given speed, although the reduced weight of the tire, and less friction if it's also a narrower tire, would offset the fuel loss to a degree.
On the flip side, if you put an overly large tire on the car, it should be like changing switching it to a taller (numerically shorter) axle ratio. Nowadays though, the stock tires tend to fill out the wheelwells in cars, so I don't know if you have as much wiggle room as back in the day, to go larger.
(>2000lbs) and gutless (40HP) as they were Beetle mileage was not impressive, my 100HP Triumph got the same 27-28 highway mpg as my Beetle and it didn't have an overdrive gear like the very high 4th in the Bug.
Those Beetles were reputed to get 30MPG but I consider that mythical since you had to drive with the gas to the floorboard to maintain safe highway speed. To this day I tend to accelerate going up hills just because..I can.
2001 BMW 330ci/E46, 2008 BMW 335i conv/E93
I wonder too though, if there's something about old Bug's suspension design or brake assemblies that might have required the greater clearance of a larger wheel?
At first I was thinking maybe it was the swing axles that required more clearance and a bigger wheel, as the '61-63 Tempest also had swing axles....and 15" wheels! But the Corvair also had a swing axle, but probably just rode on 13" wheels standard.
Why does a pick-up truck need to ride on 20" rims with 275 mm tires?
Why does the new 4-cylinder Venza (latest Camry wagon) coming this fall need to ride on 20" rims with 245 mm tires? Think how much gas these two could be saving with appropriately-sized tires.
And among pick-ups, Ram is far from the only offender, it is just the worst.
2014 Mini Cooper (stick shift of course), 2016 Camry hybrid, 2009 Outback Sport 5-spd (keeping the stick alive)
I just looked up replacement tires on Tirerack. The Ram actually comes standard with a 245/70/R17 tire, which I guess isn't too over-the-top these days. Cheapest replacement tire they had was $110 apiece. The 275/60/R20 is optional though...and not as expensive as I thought it would be. Starts at $138 apiece.
Of course, that's the cheapest of tires. Tirerack's most expensive 275/60/R20 is $234. In the 245/70/R17, they go up to $195, but that's for a deep-groove, off-road type of tire. Their equivalent of the $234 20" tire is "only" $181.
You figure, $234 for the tire is about $280 out the door including tax, mounting and balancing, tire stem, and disposal fee. So my $300 estimate wasn't too far off. Thanks for clarifying that they had 20" rims, I couldn't remember if it was 19 or 20. :-)
The only reason the Ram came with 20" rims was to make the whole thing look as menacing and bad-[non-permissible content removed] as possible. Now Ram owners are paying the price for THAT little folly...
2014 Mini Cooper (stick shift of course), 2016 Camry hybrid, 2009 Outback Sport 5-spd (keeping the stick alive)
Oh and those tires will most likely last less then 25,000 miles.
2014 Mini Cooper (stick shift of course), 2016 Camry hybrid, 2009 Outback Sport 5-spd (keeping the stick alive)
They are just really big tires and are 4x4 performance all seasons with a low tread wear rating. The OEM tires are 318 bucks from tire rack but that is a lot less then what our parts department charges us.
Changing the tire diameter is effectively changing the gearing. If you keep everything else the same, changing the aspect ratio will accomplis that. As a very rough rule of thumb for metric sizes, adding 20mm to the tread and subtracting 5 from the aspect ratio will keep the tire diameter the same.
The parts department makes most of the money at a dealership. Service is second and then sales always gets the shaft. Most sales departments at mass market dealers don't' even make a profit and some operate at a loss continuously.
That's counterintuitive. Are you sure about that?
When I got the 255/70/R15's on my Silverado back in early 2006, I think the tires were around $375 delivered, from Tirerack, and the local mechanic charged something like $100-125 to mount & balance them, do the valve stems, etc. It was around $500 total, I remember. I thought it was pretty pricey at the time, and started regretting that I didn't just put the stock 235/75/R15's back on. I think that would've only saved me about $40-50, though. I might just put the stock size tires back on the next time around. The wider tires seem to help a bit with hard cornering...not that I do that on a regular basis in this truck! But they also seem to react a bit more noticeably to imperfections on the highway, such as the ruts left by heavy trucks.
Next time around is probably a long ways off though. In the 2 years and 3 months since I got those tires, that truck hasn't even gone 10,000 miles.
The sharpest-handling car I ever owned personally wore 195 mm tires. An '02 Celica. That thing cornered on rails. Of course, it helped that it weighed only slightly more than 2400 pounds. The '04 RSX I owned later was less sharp, despite wearing 205s. Of course, it also weighed 300 pounds more. Even tires like the stock 225s on the S2000 are probably overkill, put there to look good (in person and for specs on paper), when 205s or 195s would serve just fine in such a small, light, low car.
2014 Mini Cooper (stick shift of course), 2016 Camry hybrid, 2009 Outback Sport 5-spd (keeping the stick alive)
I think more cars these days have bigger rims, only because they look better. I truck with small rims, doesn't appeal as much as a truck with nice big rims to go along with them. But, replacing them is more expensive, if you get the cheapest model to replace them, then its only sooner you'll have to do it again. I have 08 Pontiac G6 with Hankook optimo tires on them, I have seen this tire with like 42k miles on them, and they seem to wear pretty good. I don't see me having a problem, because I lease, so I will be no where near that mileage, and I don't drive hard. Keeping tires rotated helps out so much. Having slimmer tires could help getting better mileage.
Better solutions include changing the tire tread design to reduce rolling resistance and eventually doing away with the inflated tire completely (remember Michelin's unusual non-pneumatic tire design from a few years ago?) to drastically reduce the unsprung weight of the tire-wheel combination.
Gee you'd think I was slipping and sliding all over the road with the 165/75-13s on my Fiat Spider. Like most roadsters of the day it's handling was precise and predictable because the cars were light and well-balanced.
As gas mileage becomes more important cars will be built smaller and lighter, and will provide great handling, braking and safety using narrower, taller tires.
2001 BMW 330ci/E46, 2008 BMW 335i conv/E93
I remember when most generic family cars back in the day came with a 75-series radial standard. For instance, the 195/75/R15's on my 1980 Malibu, or the 205/75/R15's on my grandmother's '85 LeSabre. My old '69 Dart had bias-ply tires that roughly equated to a 195/75/R14. With cars like this, it seemed like going down to a 70-series, but bumping up one, maybe two tread width sizes was all it really took to improve these cars' handling considerably, with little loss in comfort. But going down to a 65 or 60-series tire would just make it ride rougher without giving you any better handling. As for tread width, go too wide, and those tires will get downright scary in wet weather!
I do not like the direction the market has taken us with lower and lower profiles on taller wheels. So often we buy cars from manufacturers that insult our intelligence on a regular basis. They see a young man wearing his baseball cap sideways or backwards that has blinged out his Civic with tall wheels and lowered suspension, and the next thing you know they assume that's what the whole nation wants. The same could be said for the number of transmission gears race that is taking place lately. There is no need for 7 and 8 speeds and in many applications, even 6.
As for the big wheels, hopefully it will be sooner than later that that fad wears off. The advantages of lower fuel consumption, more acceleration, longer tire life, less cost, easier balancing and better ride are all right there for waiting. Are you listening, Manufacturers?
Sam
I recall seeing an ad for the 1940 Plymouth offering 20" wheels marketed to rural customers to compensate for poor road conditions.