I acquired a set of 16"x71/2" wheels and 225/50 Dunlop tires for my '85 535i. Two tires are brand new SP8000's and two are about 1/3 worn D40M2's. My thinking is that the 8000's should have more grip, and that mounting them on the back will tend toward understeer and oversteer if mounted on the front. I'm doing a driver's school in a week and a half and would like a recommendation. Thanks in advance.