Yes the offset is one factor. As I understand it, the 9.5" wheel is for a M3. Their rear fenders are flared and can take the fit. The offset for a 8.5" wheel should be about 38 to 40mm. The offset for a 9.5 should be about 35mm. I've seen posts here and on other forums about the rear wheels. Any car that has been lowered, 235's are the biggest without any rubbing problems.
1995 325I, tinted windows, K&N, debaffled air box, BMW style #104 wheels, Nighthawk low beams, smoked side markers, smoked corners, smoked taillights, M3 style heated mirrors, various interior bits, Bosal cat-back