Does how WIDE a wheel is make a difference?

[mareakin]

I guess for most people, the wheel is a constant--instead, you choose what tires you want and usually most folks choose the OEM size.

Far as I know, most tire sizes are spec'd to be mounted on a range of wheel widths.

Let's consider General ALTIMAX HP 195/60/15 tires. These can be mounted on 15X5.5 to ---> 15X7 size wheels.

Question is, does it make a difference? Whether they are mounted on 5.5" width wheels or 7.0" width wheels?

Here's what I think (maybe because I read it online somewhere): The sidewall of the tire will be STIFFER mounted on a wider wheel. Has to do with convex shape of the sidewall.

Please chime in. Thanks.

 

[Shannow]

Rim width will change the way that a tyre behaves with a sideways loading, and the angle which the tread makes to the ground as the vehicle loads up/rolls.

Try visualising trapezoids starting with a really narrow top/wide bottom (skinny rim, wide tread), to a really narrow bottom/wide top. Visualise pushing them sideways, and see how the tread rolls away from the road, or into it.

 

[CapriRacer]

Here's the theory:

As the rim width gets narrower, the tread will tend to arch across its face. That results in a tendency towards center wear, a tendency to follow the ruts and grooves in the pavement, a vagueness to the road feel, and a sensitivity to the wind.

As the rim width gets wider, the tread will de-arch across the tread face. That results in a tendency towards shoulder wear, more sensitivity to steering input, and a sensitivity to suspension travel.

If you stay within the ranges published, these differences are pretty minor, and for practical purposes can be ignored.

 

[mareakin]

In short, wider is indeed better!

 

[CapriRacer]

Originally Posted By: mareakin
In short, wider is indeed better!


Perhaps my explanation wasn't clear. There is a change, and whether you interept that as an improvement is dependent on what you are trying to accomplish. Many folks would see a tendency towards more shoulder wear, and other sensitivities as counter productive.

 

[dailydriver]

If you want to see some EXTREME, maybe even dangerous examples of a wheel MUCH too wide for the tire, check out the Bosozoku-style rides in Japan!

Some of them put a 195 section tire on a 10+" wide wheel!!!!!

 

[fsskier]

I will go with wider when available. Most rims are much wider now than years ago..... lets go back to the 60's.

I had risen to the top of the autocrossers, gymkhana's, etc and took handling seriously, installing anti sway bars, better shocks, springs, and read every thing available on suspension design, etc.

NOTHING made as much difference in the handling as changing from the 5 inch rims, common at the time, to 6 inch rims. Huge, immediate increases in steering response, reduction in slip angle, stability, decrease in darting on shoulders, etc. \

Changes large enough that others driving your car noticed immediately.

At the time many station wagons had wider rims.... who would have thought a simple swap ($1 per rim) at the local junkyard could have yielded such huge gains.

Now, no modern car that weighed 4,000 lbs or more would have rims only 5 inches wide..... and handling is greatly improved through this one simple change.

Edge wear??? With plenty of pressure, I have never had problems with that.

 

[XS650]

Originally Posted By: CapriRacer
Originally Posted By: mareakin
In short, wider is indeed better!


Perhaps my explanation wasn't clear. There is a change, and whether you interept that as an improvement is dependent on what you are trying to accomplish. Many folks would see a tendency towards more shoulder wear, and other sensitivities as counter productive.


All in moderation....now.

If the 1960s with [censored] bias ply tires you could get much improved handling out of the tires by going wider than the Tire and Rim Manufacturers Association recommendations and upping the pressure for even tread temperature. I considered their max rim width recommendation as a reasonable minimum. I think I got better tire life that way, I know they ran cooler.

That's ancient history now though, I don't see any reason to go over the recommended max rim width now and would be hesitant to do it with modern tires.

 

[Old Mustang Guy]

I recently upgraded the wheels on my 06 Mustang GT from 17x8 to 18x9. The section width of the tire (both times Kumho ASX) stayed at 255 but handling improved significantly. I know that the 18" tires have a shorter sidewall (maybe stiffer) which may improve handling but I am thinking that the wheel width was the main factor.

 

[Quattro Pete]

Originally Posted By: Old Mustang Guy
I know that the 18" tires have a shorter sidewall (maybe stiffer) which may improve handling but I am thinking that the wheel width was the main factor.

Going from 17" to 18", you added an inch of rim and you took away an inch of rubber from the sidewall - that probably had the biggest effect. The actual tire brand/model/speed rating may have affected sidewall stiffness (and hence steering response), too.

 

[HTSS_TR]

Originally Posted By: Quattro Pete
Originally Posted By: Old Mustang Guy
I know that the 18" tires have a shorter sidewall (maybe stiffer) which may improve handling but I am thinking that the wheel width was the main factor.

Going from 17" to 18", you added an inch of rim and you took away an inch of rubber from the sidewall - that probably had the biggest effect. The actual tire brand/model/speed rating may have affected sidewall stiffness (and hence steering response), too.

I agree.

 

[woodibly]

It's best to stick with the proper width for the wheel such as 235 for 8", 215 for 7", and 195 for 6" I think?

I'm in the camp of changing compound rather than width unless you change wheel width. If you go too wide for a wheel, it can degrade steering feel and if you go too narrow, the tires can be too stiff. These symptoms are more extreme with low profile tires.

 

[dailydriver]

Originally Posted By: woodibly
It's best to stick with the proper width for the wheel such as 235 for 8"


There are people in spec competition classes using a 255 width tire (50 series aspect ratio) on an 8" wide wheel.

Granted those are 100 treadwear, probably MUCH stiffer sidewall than ANY street tire, D.O.T. road race tires, and the rules state that they cannot use any wider a wheel than 8", but still they are going pretty durned fast on those setups.

Some stock class autocrossers on those same wheel width limitations actually go up to a 265/45 tire on their 16x8 wheels

, although they will obviously admit that is NOWHERE NEAR optimal.

 

[Ramblin Fever]

I run 265/75 tires on my 16x8 wheels on my truck....something wrong with that?..referring to the post directly above.

This was actually the size of tire recommended to me by the tire shop for the width of this rim; they said it was perfect.

This same truck once had 16x6 rims with 225/75 tires from the factory.

Widening the rims and tires made a HUGE difference on stability, cornering, etc on this truck...over 100% improvement.

 

[Old Mustang Guy]

I think you are ok but 265 would be about the max. The fact that it is a 75 series makes it even better since the sidewall will be more flexible. I had 255's on my Mustang on 17x8 wheels before I upgraded to 18's. 255's were considered to be the maximum width on that wheel.

 

[Ramblin Fever]

Yeah...I don't plan to go any bigger. A 265/75 tire, for a good A/T is already at the upper $170+ range....I have 3 trucks running this size.

I will say my cummins diesel came with 16x7 rims and 245/75 tires; we have since installed 265/75 tires on it too, with greater stability.

 

[Zaedock]

I run 38x15.5 Baja Claws with 15x10's on my Jeep. The narrow rim width helps keep the beads on without beadlocks.