My experience has been that if the roads are good enough to drive, they are good enough to bike. Once the plows & salt/sand spreaders have been through, it's usually fine. I like biking when there is visible snow & ice because the motorists are much more cautious and polite.
I don't have special tires for winter. If I lived further north I might but in Missouri the snow & ice doesn't stay around for long.
Good luck, you're going to love winter cycling! You are so hard-core!
2009 Trek 7.2FX WSD, brooks Champion Flyer S, commuter bike