My 88 735i gets a scraping noise after having been driven awhile. I will drive on the freeway and then when I exit and drive on surface streets the noise can start. It doesn't always happen. When it does it sounds like playing cards against the spokes of a bicycle wheel. If I get back on the freeway the noise goes away or after the car sits away the noise is gone. The noise occurs when the car is moving and the faster the car moves the faster the noise occurs. Any ideas what I should look for?