Step 14: Winter Tires
These can be expensive, but they are totally excellent on hardpacked snow or ice. Beware - in soft snow, they are just like regular tires - slippery.
One can manufacture snow tires using regular knobbly tires, 300 or so 3/8 inch Robertson screws, an awl , a square tip screwdriver, and a couple of days worth of time. I'll try to dig up a recipe for them. Beware, snow tires have a lot of rolling friction, due to their studs, and feel different handling wise. They are kind of like wearing heavy boots: After a season of using them, you'll be amazed at how summer tires roll so easily. My wife bought me my studded tires (Shame on me) and I chucked out my homemade ones (More shame on me).