If they are a stock replacement for most of those cars, the rims size is usually 7.5"

The way those tires sit on the edge of the rims, it also makes me think that they are a 7.5" max. On an 8" wide rim, a 215/50 would be stretched so bad that you wouldn't get a correct contact patch. JMHO

 

Tire Rack lists the 18"s at 7" wide.
They are being discontiued it seems. No 17's left there.

 

Batman im about to be buying these with some Nitto 555s in 245/40/18

http://www.discounttiredirect.com/pr...d19.blm.xl.jpg