Dumb Question?

bmdupont · February 3, 2009

Ok so this might be a really dumb question but ill ask it anyway.

Got a 08 SD with the stock 20’s, if I replace the stock wheels with some aftermarket ones will it affect the ride of my truck at all?

I wouldn’t think it would change since they are on the same tires and same size wheel but I have some little doubts????

What about if I put 22’s on it? I know you can get the 22 OEM wheels so I wouldn’t think aftermarkets 22’s are going to change the ride and feel much???

The reason I ask is because before this I had an 02 Tahoe that I put 20’s w/Goodyear GT II’s on and by the time I got to 60k miles that thing was like herding sheep down the road, it drove me insane. Plus my power steering pump had to be replaced at 50k.

I really like the ride of the Sierra Denali and am afraid I might mess it up.

superjim · February 3, 2009

There are always exceptions...but....

If you go with some other 20 inch wheel, and use the same tires you have now...there will not be any difference in the ride.

If you go with 22 inch wheels and lower profile tires, (to keep the same overall diameter) then the ride will be rougher and more harsh then it is now.

The sidewall of the tire acts sorta like a shock absorber for smoothing out potholes, pavement dividing strips and other imperfections in the road surface.

Therefore, (in general), the thinner the sidewall between the edge of the wheel and the road...the harsher and rougher it will ride.

Spurshot · February 3, 2009

Just a bit on tires: every tire design has a "spring rate" or something akin to a spring rate. That is; the tire soaks up some of the road irregularities itself. Generally, if the tire has a shorter sidewall, it likely will have a higher effective spring rate...transfer more bump energy into the suspension of the vehicle. The same may be true of higher load rating tires of comparable size. Stiffer sidewalls transfer more energy into the suspension. That's why some tires have rougher rides than others even when comparing identical sizes.

Wheels gererally don't have as much spring rate effect as tires. They do have effects from "unsprung weight". Unsprung weight is the weight of all the suspension and rolling components that move up and down as a result of bumps in the road. If it's higher, the higher inertia will do things like make the tire loose ground contact more of the time, reducing traction on rough surfaces. The tire/wheel combination generally has the biggest variation potential in unsprung weight when we modify our vehicles. Big tires are heavy. Wheel weights are all over the place. Forged aluminum wheels generally can be lighter and/or stronger as well. That's one big reason why not many race vehicles use cast aluminum wheels.

So, if you use the same tires and maintain the same wheel weight or very close, maintain the same offset, you shouldn't see a ride quality change. If you buy some significantly lighter forged aluminum wheels, you may notice an improvement in traction on bumpy cornering compared to the original limits of traction on the same surface.

bmdupont · February 3, 2009

Oh this is good stuff thanks . I have wondered this for awhile. When I upgrade my tires is this something the tire dealer should know? I mean if I lay on him the spring rate questions is he going to understand what im talking about?

Or is this something I should do my own research on before and decide on a tire/wheel before hand. Think this time around im willing to sacrafice some performance if I can get the same smooth ride as I have. I will have look up the spring rate of my current tires so I have something to compare with.

I would imagine if I went with 22's I can get the same sidewall as with the 20's and live with some rub.

Thanks for all the info, hope this post can help some other people too