They will fit something (probably a G29 as the M40i comes with 275/35 rears already).
I wouldn't try them on a e85/86 though as I've run 265/40r18 SuperSports since they came out, and they will rub occasionally on mine (even before the car was lowered a bit). Even the 265/30r19 on CSLs rubbed when I first got the car. It's not like it rubs for every mile of every trip, but you'll hear them catch the arch/liner when pressing on, or when you go through a series of undulations.
e89 would be a tight fit too, as standard biggest tyres on that were 255/30r19, so you're looking at both an inch wider and inch extra on the sidewall.