[pdxmotorhead]

You need lbs per square inch, lots of little edges (Sipes) and run a lb or two lower tire pressure but keep the 2 to 4 lb split front to rear (Its on the door sticker near the latch)
The BMW sizing for the all weather and ice tires is on that tag as well. And if you have adjustable shocks or sway bars soften them up.

Dave