I have 10.5 Chrome 03-04 Cobra rims on the back of my stang and that is the widest u can go without modding the wheel well. that is a 315/35/17 tire on the back and it looks sick. if u want a pic just let me know.
also don't look at AFSwheels.com they are over priced. all the wheels they have there you can find at oeconcepts.com i believe oe concepts makes the wheels and they are cheaper there. That is where i purchased mine.
If you want 11+ you need to start looking at a smaller rear end. There is no room for something like that. Start cutting up the wheel wells and relocating your suspension.