oggle

Ok I'm a newbie when it comes to wheels and tires. I read a bit about wheel offsets and understand the basic concept. However, I need to know, what is the proper offset for a C class sedan and how is it adjusted when new wheels are added? Spacers?

Luke@tirerack

wheels are typically manufactured with the offset built into the design of the wheel .... Spacers are widely considered to be a bad idea unless they are hubcentric and designed for a specific application

KWiK

There is no single proper offset. For any given wheel width, there are a few offsets that usually work. This assumes a reasonable wheel width, say 7.5" - 9.5". Even with a proper offset, getting a tire that is too wide you may still have rubbing.

Using my stock C7 wheels, my 18" Evo5 wheels and some spacers, I did a little playing along with some math, this is what I think is the best fitting wheel tire combo:

Front: 18x8 et 32 225/40
Rear: 18x9 et 32 255/35

This combo looks good with a wider tire like the Bridgestone S-03. I don't suggest a narrow tire like the Kumho 712.

oggle

Can you explain the parts I've put in bold? I don't eve know how to read these things lol.

KWiK

the 32 in your bold is the wheel OFFSET

the 35 you have in bold is the tire Aspect Ratio

Those links and many other helpful wheel & tire pages are available at the TireRack TechCenter

oggle

Thansk KWik. I am learning a bit more, although it's still a blur to me as I've nothing to compare those numbers to. I'll get it some day.

KWiK

Pull off one of your stock wheel and read the size & offset to help picture what a different offset would do

Luke@tirerack

read the tech posts in this forum and you will understand better