Are you FULL of AIR? Your TIRES, Silly! It is VERY important to maintain the correct amount of air pressure in your tires during the WINTER. Maintaining the correct air pressure in your tires during the winter is a little more difficult than the warmer months. This is because when the temperature drops so does the air pressure in your tires.
For every 10*F the temperature drops your tires can lose 1 lb. per sq. in. PSI of pressure. So just keep those tires within 5 lbs. PSI of what the manufacture recommends on that model of tire. And just keep and EYE on those TIRES this WINTER!