Currently I have the 01-06 M3 18's on my car. I believe the Rear Rims are 18 x 9 and the tires are 235/40's. When going through the dips and if there are passengers in the back seat the tires will rub on the sidewall and inside of the fender. Just wondering if anyone has had this same experience and if so how narrow do I have to go to get clearance? and how narrow can I go and still fit the rims?