I did last two winters on 225/40/18 Blizzark LM-22 all round. One of the winters in a ski-resort up there, and am only 2WD. I was amazed how well they performed. For comparison, I also have a RAV4 4WD and would be far off if I told you on a road, the BMW came close to matching the RAV4's asuredness. Ofcourse RAV4 has all seasons on, and you woundn't dare go far off road even with the Xi since we lack the ground clearance the RAV4 has, but still, that is saying something. I just got a set of 225/40/18 blizzark LM-60 from Gary@TireRack and I am just blown away at just how aggressive the tread on these is. Way better than the LM-22s I bought from him previously. I spent more than a decade up there, so I know your winters well, and you can't go wrong with these or even the LM-22/LM-25. I'd get the newer LM-60 or LM-70 in 225 if I were you. They are better than the dunlops, and IMO you don't need the compromise of the Michellin ice.
