Been looking but can't find rear tire size for 2007 C if I want to go bigger than the stock 265x18. Want something that doesn't require any mods and no rubbing.

 

If you have a C2 you can go to the 19" tires for a C2 or C2S no problem, the C4 and C4S wheels are a little more problematic. I have the 19" Carrera Classic wheels on my 2007 C2.

 

I run a 315/30/18, my wheels are set out to the edge of the fender and the car is lowered. No rub at all.

 

My C2 is running on 305/30/19s on the rear. Looks good, no issues.

 

To OP: no mods means no different wheels, so just call TIRERACK with whatever your wheel size is -- probably 18-10 -- and they will tell you how wide you can go. I'd guess it is 275 mm and you won't see or feel any difference.