These directions come from The Edmonton Bicycle Commuter's Society, I volunteer there and you will also find these instructions at icebike.org
This is what you need to make your very own studded tire:
1. One tire. You need a tire with knobs big enough to support the stud. Slick tyres can also be studded but the stud will have less support.
2. 50 (approx.) Robertson head #8 by 1/2" sheet metal screws (the square head / socket, you'll thank me for this tip) for mountain bike tires (26inch) or #8 by 3/8 inch for hybrid tires (700c). The Robertson screw is a Canadian invention and has the benefit of being self centering and very hard to strip
3. Liner for each tire. This can be made by cutting the beads off an old tire, cutting out the valve and slitting along the inside of an inner tube or just buying a Mr. Tuffy tire liner.
4. Baby powder.
5. One sharp awl. (or a 1/8" drill bit)
* Count the knobs and evenly spread out the 25 screws for each side.
* Punch holes, from the outside of the tire, into the designated knobs. You can drill the hole, however, drilling tends to tear the fabric and thus weakens the tire. Caution you don't need a million screws in there! Too many screws just slows you down.
* Use Robertson bit in the drill to drive the screws in the tire from the inside.
* Put the tube inside the liner and then mount the tube and liner in the tire, making sure the liner covers the screw heads.
* Put a generous dusting of baby powder between the liner, tube, and tire .
* Mount tire on the rim (ouch! watch out for the points!)
* Inflate to maximum pressure. Put the wheel on the bike (mind the points). Spin the wheel to make sure that the studs don't catch on anything.
* One extra step that many people do is to use a grinder to remove the sharp points of the screws and this can also aid in giving you proper fender clearance.
You only need to stud the front tire to keep upright; however, if you stud the back tire as well, it's even better. One caveat is that these tires are only suitable for winter conditions. The difference between one studded front and no studded tires in phenomenal. When the bike is travelling straight the studs shouldn't be hitting the road too hard; otherwise, they will just wear out too soon. Don't worry, when the tire slips just a bit the studs will bite in. You rarely notice the slight side to side movement.
You don't need to stud the middle knobs since you only need the added traction when you are turning. The studs should touch the road enough to allow sufficient braking. The studs in the middle knobs wear out very fast and soon become useless anyway.
Stainless steel screws will last much longer, but also cost about 3 times as much. You can change screws as they wear out, your tire can survive several sets of studs.
Edit October 21, 2009 - The number of screws you use can be varied depending on the conditions you ride in. I like to run 50 per side and my last build has 104 studs.