Hi,
On the Z4 ground clearance thread, I posted a bunch of details on driving the Z4 3.0si/Z4 M Coupé/Roadsters in snowy climates. Including fair bit of information on appropriate snow/winter tires. You can find that post here:
http://www.zpost.com/forums/showthre...676#post708676
Sorry I did not respond in this correct thread, but it kind of touched both subjects as the ground clearance is obviously a huge issue with winter climate driving.
Best regards,
Jussi