http://www.1addicts.com/forums/showthread.php?t=252882
in case anyone wants wide tires without shelling out for wheels...
based on my results, 245 will likely work too. there's still a fair amount of space toward the strut, and the wheel doesn't seem too narrow to go up even one more size. definitely out of spec, but may be useful in the track arena. i didn't use a spacer, and there's ample fender space as well.
i used 255/40-18 on my oem m3 front wheels (18x8) with no adverse effects, so 245 on a 7.5 should be quite similar.