Bicycling is an efficient and health-conscious mode of transportation. And if you live in a region prone to icy winter weather, it's often treacherous, too. You can make your ride more secure by adding homemade snow and ice tires.
For starters, you'll need a set of tires that you don't mind puncturing. You'll turn the tires inside out and then drive screws (such as pan-head screws) so that the tips emerge through the riding surface of the tires. The exact length of the screws depends on your tire tread, but understand that you want the tip of screw to extend about a quarter inch past the rubbery knobs on your tires.
To get decent coverage, you'll probably need 200 or so screws. As you drive them through the tire, be sure not to twist the rubber. That may mean using a screwdriver or the low-torque setting on your drill. Use the same pattern all the way around the tire for consistent grip.
Install tire liners to protect the tube from the screw heads. And consider lowering your tire pressure a little for better traction in slippery conditions.