Michigan law enforcement and public safety workers across the state contribute road condition information that is provided to the public at http://www.ohsp.state.mi.us/rw/home.htm. This service is provided during Michigan's winter months -
September to June (just kidding) Late November/Early December through March 30th.
Simply click on the area of the Michigan map that you want road conditions for and you will be taken to a page that lists road conditions for the major trunk lines and freeways in that particular area. Rural and county road conditions are rarely (if ever) provided.
For example, I clicked on southwest Michigan and some of the information provided was the following:
I-94 Between Kalamazoo and Battle Creek is reporting Icy, Snow Covered, Drifting Snow, Blowing Snow, and Lanes Reduced.
Of course, if you are out driving and things get dicey it is always best to just stay off the roads. Use the information provided at the above website to help you plan, but don't forget to use your head for more than a hat rack.