I was running a 235/45/17. Admittedly those are probably a little bit big, but IMHO something like a 215/40 is way too short and looks funny. Once I set the alignment up with 2.5* camber in the front I had no more problems, then when I went with the 17x8's with a 45mm offset I really had nothing to worry about. Even if the tires don't rub, they may to stick out and look funny with a 30mm offset. Just my personal tastes, everyone has their own opinion.
John