I have been banging on for years about how different tyres front and rear 'can' cause all sorts of issues on BMWs.
On the RWD the traction light comes on a lot with mixed tyres, that shows you just how much traction you are losing.
You can also be fine, but why risk it on 'The Ultimate Driving Machine'? Just get 4 that match and know your car is right.
If you start mixing and matching tyres you may as well have bought an Audi or a Prius.
