I just had my 225/45/18 installed on my stock MS6 with stock rims, and I don't know how people go ANY bigger without mods or rubbing. My upper control arm is literally millimeters from impacting the tire when parked and tires straight. After a few hard corners, I'll check the inside of the front tires for wear. I expect I'll need at least a 5mm spacer on the front. Then again, neither the front OR rear seem to look right in the wheel well when viewed from front or back, so I might end up doing spacers all around just to get the tires out and nearly flush with the fenders.