When was the last time you checked your tire's air pressure? If the answer is some time last season, get the air pressure gauge out and take an accurate reading. Did you know your tire pressure can dip 1 psi for every 10ºF drop in temperature. The change in air temperature could mean your tire's air pressure is significantly lower than the recommended amount.
A properly pressured tire is better suited to deal with slush and snow as its contact patch is working at its peak efficiency. It is important to note that if you take the reading in a warmer garage, consider adding three to five psi higher than recommended, as the car will be operating outside the insulated garage.
For more winter tire pressure tips check out this tech article.