I run 17" Pilot Sports in the summer on my E36 coupe. Useless in the snow. Just got Blizzaks on steel wheels, and it's like driving a different car. I've had no trouble at all. Plus, the fact that the tires are half the cost of the Pilots means that it pays for the wheels in just a couple of winters.

I highly highly recommend Blizzaks for any Bimmer, esp. those with wide-profile tires.