Ask the Car People.SM


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

62 messages,  Last post on Jun 27, 2011 at 9:33 PM

You are in the Automotive News & Views-Archives Forum.

What is this discussion about? Tires

Messages Page 3 of 7

#13 of 62 Simple Logic by hpmctorque

Jun 11, 2008 (9:39 pm)

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.
 

#14 of 62 Re: Simple Logic [hpmctorque] by lemko

Jun 12, 2008 (6:05 am)

Replying to: hpmctorque (Jun 11, 2008 9:39 pm)
I guess we'll be seeing less of those blingy wheels. They just keep spinnin' and spinnin' and spinnin'!

#15 of 62 Re: Simple Logic (lemko) by hpmctorque

Jun 12, 2008 (6:41 am)

"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.

#16 of 62 back in the day by nippononly

Jun 12, 2008 (7:26 am)

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.

#17 of 62 Re: back in the day [nippononly] by andre1969

Jun 12, 2008 (8:22 am)

Replying to: nippononly (Jun 12, 2008 7:26 am)
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.
 

#18 of 62 Re: back in the day [andre1969] by andys120

Jun 12, 2008 (10:11 am)

Replying to: andre1969 (Jun 12, 2008 8:22 am)
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.

#19 of 62 Re: back in the day [andys120] by andre1969

Jun 12, 2008 (10:43 am)

Replying to: andys120 (Jun 12, 2008 10:11 am)
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.

#20 of 62 Re: back in the day [andre1969] by andys120

Jun 12, 2008 (11:48 am)

Replying to: andre1969 (Jun 12, 2008 10:43 am)
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.

#21 of 62 Re: back in the day [andys120] by andre1969

Jun 12, 2008 (12:06 pm)

Replying to: andys120 (Jun 12, 2008 11:48 am)
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.

#22 of 62 just walked past by nippononly

Jun 12, 2008 (12:29 pm)

a Dodge Ram in a parking lot, and it is like the 3rd one I have seen in a couple of weeks with totally bald tires. Nobody who bought those things thought for even one second about how much it would cost to replace 19" or 20" tires, LOL. $300 apiece at least, I bet.
 
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.

Messages Page 3 of 7

Advertisement

Browse by Category

Browse by Vehicle
   View All Vehicles

Browse by Board
Browse by Topic
View All Topics

Edmunds Community

Advertisement