you can even go as high as 20's with rubber bands for tires.... you forgot to mention offset. That will make or break you on the rubbing. I personally can't tell you if it will rub or not but you will need to at least mention offset. I know several people run the RX-8 wheels which are 18's
225/40/18 with +40 offset will most likely rub, especially if you're lowered. Is it an 18x8 wheel? 215/35/18 will fit on 18s, I wonder if 215/40/18 could as well.
I run 215/40/18 with +55 offset. I also run Illumina struts and s-tech springs. On the softer settings, I would rub a lil bit on the fender if I hit a bit enuf bump. Stiffened up the setting and I don't rub anymore
