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Will Narrower Tires With Taller Sidewalls Return, To Improve Fuel Economy?

hpmctorquehpmctorque Posts: 4,118
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?
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Comments

  • 1stpik1stpik Posts: 495
    If times are so desperate that GM finally admits it can no longer churn out 15 mpg vehicles and stay solvent, then, yes, everything's on the table.

    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.
    .
  • lemkolemko Posts: 15,067
    ...to cars like my 1988 Buick Park Avenue. Its 3.8 V-6 only churns out 165 hp, but its adequate enough for a decent getaway from the traffic light or cruising on the highway. It also has wider sidewall tires than my 2007 Cadillac DTS w/18" wheels that look like rubber bands in comparison.
  • andre1969andre1969 Posts: 21,578
    but a couple years ago, I replaced the 235/75/R15 tires on my '85 Silverado with 255/70/R15's. Slightly larger diameter: 30" versus 28.9", and about 3/4" wider tread. Revs per mile reduced from 719 to 692, so that could make the speedo and odometer read about 3-4% low.

    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?
  • kernickkernick Posts: 4,072
    I believe much of the reason for making tires wider have been to provide better handling and braking, with our cars. The more friction the better for those attributes. So 1 of the questions is are you willing to lower the safety of the vehicle to get better mpg.

    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.
  • andys120andys120 Loudon NHPosts: 16,379
    As cars get smaller and perhaps lighter the relative size of their tires will undoubtedly shrink a little. The Tire Rack recommends 185/65/15s for a Prius which is around the same size worn by my first car to wear radials back in '69. It was a TR-4A, weighing about a ton wearing 185/75/15 Dunlops SPs.

    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:
  • hpmctorquehpmctorque Posts: 4,118
    Plus, narrower tires provide better traction in snow.

    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.
  • Stever@EdmundsStever@Edmunds YooperlandPosts: 38,919
    I liked my skinny tires I had on my old '82 Tercels. They did good in Anchorage winters, and I could buy a whole new set for like $80. 14" rims iirc.

    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?
  • explorerx4explorerx4 Central CTPosts: 9,444
    91 mustang gt 'vert 225-55-16
    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.
  • andys120andys120 Loudon NHPosts: 16,379
    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.
  • hpmctorquehpmctorque Posts: 4,118
    "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."

    It would be interesting to know how much mileage would improve if tires could be inflated to 50 psi, or 60, say.
  • british_roverbritish_rover Posts: 8,476
    The OEM tires on my MINI could be inflated to 51 psi but I wouldn't recommend it unless you wanted some teeth removed.
  • hpmctorquehpmctorque Posts: 4,118
    For the past several years tires were reconfigured, to a great extent, to conform with ever increasing horsepower and weight. The power increases yielded faster acceleration and speed, which, in turn, required tires to deliver this higher level of performance to the pavement, plus stopping and turning improvements to match the increased straight line performance. Wheels and tires were increasingly designed for spirited and aggressive driving. They responded to the quest for better and more impressive numbers.

    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.
  • lemkolemko Posts: 15,067
    I guess we'll be seeing less of those blingy wheels. They just keep spinnin' and spinnin' and spinnin'!
  • hpmctorquehpmctorque Posts: 4,118
    "I guess we'll be seeing less of those blingy wheels."

    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.
  • nippononlynippononly SF Bay AreaPosts: 12,669
    I went from 225/75 tires to 265/70s on my 4Runner, and my fuel economy dropped by about 15%. You think automakers don't know that? It is a certainty that tires will get narrower in the years to come, in the pursuit of better fuel economy.

    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.

    2013 Civic SI, 2009 Outback Sport 5-spd (stick)

  • andre1969andre1969 Posts: 21,578
    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.

    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.
  • andys120andys120 Loudon NHPosts: 16,379
    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.

    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.
  • andre1969andre1969 Posts: 21,578
    While it's true that the aspect ratio has no bearing on fuel mileage, tire pressures do.

    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.
  • andys120andys120 Loudon NHPosts: 16,379
    Andre I used to think that VW fitted tall skinny 15" tires to the Beetle to enhance gas mileage (fewer revs/mi than the 13" most econo cars wore) but the truth is that as light
    (>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. ;)
  • andre1969andre1969 Posts: 21,578
    I think the Beetle used 15" tires simply because that's probably what it used back in 1939, when it first came out. They just didn't bother to change them much over the years.

    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.
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