In the winter, tires have a harder time than in the summer:
- Roads are frequently wet, which 'lubricates' glass and nails going through the tire.
- The city does not street-sweep in winter, leaving lots of glass on the road.
- You tend not to pump-up your tires as frequently, leading to pinch-flats.
Because of these things, get the toughest Kevlar-backed tires, like Armadillos, for the winter even if your summer tires are in good shape. Nothing sucks like changing a tube at the side of a slushy road with fingers numb from the cold.