Say folks, I've read and re-read posts about not going wider than a 225 section width tire on the stock 17" rims. Is it safe to assume then that a 225/45/17 tire will fit a 7" wide rim with no problem? I'd like to avoid paying $300 or more per rim to get 7.5" width, but I damn sure want out of these crappy Potenza RE92s.....Thanks in advance!

 

Width-wise it's perfect. But going w/ a 45 series profile, it will be slightly smaller than the stock 225-50-17. So if keeping the overall diameter of the tire(ie.. correct speedo/odo) is a goal, then this is not correct.

This is the simpliest tire calculator I could find. It's a nice tool.

http://www.miata.net/garage/tirecalc.html

 

235/45/17 would be tire to go for, 225/45/17 would set your speedo off, but 235/45/17 barely sets your speedo off.