Greydog

As you run an M3 (Lucky Boy) rear wheel drive the BMW approved/star rated tyre system is less critical than on any of the Xdrive models. The star rating is more important on the xdrive models and in particular where they are staggered (fatter rear) to ensure rolling radius is within tolerance front to rear in order to avoid transmission wind up and transfer box damage.BMW now have approved Bridgestone and others in the range of tyres most fitting stations are quite happy to stick with the "approved" tyres as they are also the most expensive and earn them the best commission. I am cynical about these things.

As your car is a tail happy M3 personally I would go for the best grip.