Performance differences with stock wheel diameters

Donstar · October 19, 2016

Common stock wheel diameters on these trucks are 31.1", 31.6" and 31.9". If you compare these diameters on a rear axle ratio conversion, there is a numerical difference. My question is if I switch from a 31.1 to a 31.9 (3/4" difference) will I notice any "real world" differences in performance? I am just curious and know that this is a small change when comparing to questions about 33". 35" and 37" wheels. My question is out of interest and I would change within this range without hesitation.

Sean Neilan · October 19, 2016

Do you mean tires?

TxTruckMan · October 19, 2016

All things being equal - no. But there are a lot of other factors that come into play - wheel weight, sidewall height, rolling resistance, tread pattern, rubber compound, etc.

Donstar · October 19, 2016

All things being equal - no. But there are a lot of other factors that come into play - wheel weight, sidewall height, rolling resistance, tread pattern, rubber compound, etc.

I mean all things being equal. Stock tires on stock rims. My truck came with 255/70r 17 tires which is a 31.1" diameter while other similar trucks on the lot had 265/70r 17 tires which are 31.6" diameter.(Trucks with 265/65r 18 tires are also 31.6"). My son's High Country came with 275/55r 20 which is a 31.9" diameter tire. I imagine these are all considered 31" wheels and share the same performance expectations. I find there is a considerable difference in the appearance of these sizes and am looking at the best looking option with the least amount of impact on power. For example, if I was able to get a set of new Denali take-offs from my local dealership, would I notice any difference other than the looks?

amxguy1970 · October 19, 2016

Probably some, a wheel weighs more than a tire. 20" rims and same size tires (say 32") will weigh more than a 17 inch rim and 32" tire even if they are the same tire. You may feel some difference, probably not enough to be noticeable though.

Tyler

TxTruckMan · October 20, 2016

I mean all things being equal. Stock tires on stock rims. My truck came with 255/70r 17 tires which is a 31.1" diameter while other similar trucks on the lot had 265/70r 17 tires which are 31.6" diameter.(Trucks with 265/65r 18 tires are also 31.6"). My son's High Country came with 275/55r 20 which is a 31.9" diameter tire. I imagine these are all considered 31" wheels and share the same performance expectations. I find there is a considerable difference in the appearance of these sizes and am looking at the best looking option with the least amount of impact on power. For example, if I was able to get a set of new Denali take-offs from my local dealership, would I notice any difference other than the looks?

That isn't "all things being equal". Like the other poster said, rims weigh more than rubber. Rubber is more flexible than Aluminum. All contribute to slight differences in performance. Lower profile wheels (20" and 22") will handle better on the highway, but give you slightly stiffer ride. They'll probably accelerate a little faster if their weight isn't much higher. But lower profile tires (17' & 18") will have slightly softer ride, but slightly worse handling. And then with a slightly taller wheel you'll get slightly better mileage on the highway, but slightly less around town due to the small increase in rotating mass.

If you stick with stock (OEM) wheel/tire combinations you won't have any meaningful impact - mostly negligible. If you start going with much larger/heavier non-EOM wheels/tires, you'll have a much more noticeable impact.

kstruckcountry · October 20, 2016

The thing about wheels is that the weight has less of an effect since it's all closer to the center of rotation. Then again, my best ever mileage on 4 ply's was 18.5... Best ever mileage on 10 ply's... 18.5, for a 13% or so heavier tire. I think with "similar to stock" tires and wheels the impact will be very negligible.

I'm sure someone at GM has actual IC stats on where the weight lies on the wheel, if you had that you could easily convert it to linear momentum for comparison.

Sent from my SM-G920V using Tapatalk

Donstar · October 20, 2016

That isn't "all things being equal". Like the other poster said, rims weigh more than rubber. Rubber is more flexible than Aluminum. All contribute to slight differences in performance. Lower profile wheels (20" and 22") will handle better on the highway, but give you slightly stiffer ride. They'll probably accelerate a little faster if their weight isn't much higher. But lower profile tires (17' & 18") will have slightly softer ride, but slightly worse handling. And then with a slightly taller wheel you'll get slightly better mileage on the highway, but slightly less around town due to the small increase in rotating mass.

If you stick with stock (OEM) wheel/tire combinations you won't have any meaningful impact - mostly negligible. If you start going with much larger/heavier non-EOM wheels/tires, you'll have a much more noticeable impact.

Thanks, you are right about not being equal. I meant something like "stock factory issue". I like the looks of many of the gm factory wheels including my current 17's. However, I do prefer some of the tire options available on the 18's and 20's.