I have 18" Pirelli 240 Sottozero snows on my car. So far, I have only driven my 335i M Sport in one snow storm, with wet snow and very icy roads. Had no traction problems whatsoever, going up steep hills or braking going downhill. For extra traction, I place one of my summer wheels in the trunk and turn off the DHC.
By the way, I have driven RWD BMWs since 1984; I have never been stuck in snow, providing my car was equipped with proper snow tires. The key to success seems to be a little extra weight in the trunk and appropriate use of the throttle and brake.
For reference purposes, the 18" Pirelli 240 Sottozero II snows are the BMW Canada (and BMW NA) recommended winter tires for the F30. It would be safe to say that these tires have been throughly tested by BMW before receiving their seal of approval.
2016-328dX Touring M Sport, MPP, Glacier Silver, 18" 441M Ferric grey alloys
Last edited by DerekS; 01-03-2013 at 02:16 PM.