Try Bruno's site,http://www.bmwe34.net/ for the numerous possibilities that exist for your symptoms. Sometimes it is difficult to get it all sorted out, esp. if there exists more than one possibility. My guess is that you have at least 2 or 3 things going on. Are the rims for the snow tires centered properly on the hubs? Are they properly balanced on the rims? Others should have many ideas on the steering/suspension issues.