Did you ever find the wheel that you were going to use?

I cannot comment on 18x9.5 fitment, but I can comment on 17x9.5. I have that with 275/40/17 tires. It is tight but fits, there is about .5" between the frame & tire. I rolled the fender lip also.

http://i242.photobucket.com/albums/f...e/IMG_0248.jpg


Be careful with BMW wheels. It is a 5x120mm bolt pattern, which is 4.7244 inches. VERY close to 4.75, and will mount, but look it up, a small amount off will cause stress on the bolts & has resulted in broken studs.