Tire Rack is a good source for tires.......shop around on their website.

Well, there's basically three catagories of snow tires: the Performance Winter, the "moderate" winters, and the studdable/hard-core winter tires. The Performance Winter tires have very good snow/ice traction and will get the X3 through a foot of snow, and then some. At the same time, they'll provide reasonable highway comfort and wet/dry handling without killing steering feel. At the other end, the knobbier tires and studdable ones have superior snow and ice traction, but you're sacrificing normal condition grip and comfort.

I'm running on Pirelli Snowsport 210 which are a performance winter tire. Never gotten the X3 stuck, even though me and other folks have tried to do so in past snowstorms. Works well when you're in the dry as well. This winter will be their 4th season on our X3.

In the Performance winter catagory, I can recommend the Pirelli 210 Sottozero (the successor to mine and a bit improved). If you want something that's a bit tougher, then Continental has the ExtremeWinterContact.