17" vs. 18" rims - ride quality?

[libtech75]

I have the stock 7 spoke 17" rims on the car. I had the 18" USP/RS4s on my previous B5 A4 and I absolutely loved the look and am looking at upgrading to those same wheels (the 5x100 version) for my new to me TT.

On the A4 there was a very slight dip in harshness over bumps but not so much that it substantially degraded the driving comfort level but I did feel the difference. Keep in mind though, that was going from stock 15" to 18".

I'm worried then, the TT being as harsh over bumps as it is already, with a change to 18" rims, will the ride quality suffer that much? Or will a small one inch change in diameter really be felt at all?

Thanks for opinion guys.

[blackedoutt]

it depends on your tires really, a stretched sidewall is stiffer than a straight sidewall. I had 225/40/18 on my 18X8.5 rs4's and it made the ride noticeably stiffer. When I put the stock rims on, I could actually feel the sidewall roll into and out of turns. I want to put a wider tire on this summer for contact patch, and straighter sidewall.

[libtech75]

Of course, but I just wanted a general impression, if there way one. on an 18" rim, there aren't really going to be any touring style tires available, they are all going to be performance oriented. Naturally some tires are stiffer than others, but assuming a tire of average sidewall stiffness...

Again, on my previous A4 I went from 15" to 18" and the ride was noticeably stiffer but not uncomfortably so. By contrast, I originally had Michellin Pilot Sports and changed to Goodyear Eagle F1 All Seasons - both in a 225/40/18. Ride firmness (over bumps and cracks) was the same. Only in cornering did a notice a difference between the Max Summer Pilots and Goodyear All seasons.