
Originally Posted by
wizo
Hey,
Just ordered my wheels. I wanted a 21 inch wheel but they stated that I would probably need a 25 series tire which I did not want to do. So I decided to go 20;s and a 30 series tire. I want to keep ride comfort. I had a choice between a 255 or 275 series tire. I went 275 for added protection for the lip of the wheel and I hoped that the wheel would sit flush with the fender.
Please let me know if this will work ok. I can change my mind if this will hurt the ride. But I probably need to do this by tom. morning.

You do realise the sidewall height is dictated by the Profile of the tire, which itself is a percentage of the width. So a 275-30 (vs 255-30) tyre has a
taller sidewall (good for comfort and protection, but can push the total size outside the safe zone for the transmission, speedo etc), you seem to be interchanging 255 and 275 acknowledging width only.
I wouldnt put 20" on a C6. I have 20" on a VW Phaeton, a class size bigger. They came from an Audi S8. Originally the wheels had 255-35s that not only looked too thin but also rode badly (not as bad as your C6 will) and took excessive damage from subpar roads and potholes. Ive changed the tyre with 275-35s which gives me a little more sidewall (and I switched to heavier load rated tyres) which looks better and rides much nicer. It also allows me to used the harsher Air Suspension settings so in effect they allow for less body roll and more aggressive driving too.
IMO, super thin tyres (sidewall) look cheap and nasty. Go just a little bigger and it not only looks better, but fills out the arch and rides better too. Here is 275-35-20:
[Look at the wheel bottom to get an idea of width, the top shows the top of the tyre plus sidewall which makes it look skewed]
If you only drive on Highways and good roads, then it doesnt matter much.
Regardless of what size you take, larger tires need proportionally more PSI in them. Mine have something like 44psi in the front, IMO thats quite a lot.
Bookmarks