Bolted ice racing tires: icy grip for your frozen whip

When it comes to racing on ice, the hierarchy of grippy tires goes something like this:

5. All-season tires

4. Winter tires

3. Studded winter tires

2. Non-DOT “rally” studs

1. Bolted tires






After I sold my studded-tire equipped MR2, I was left with only my all-season tire equipped Subaru for chasing cones on the frozen lake. Even with AWD, all season tires really won’t do for that kind of duty. My admittedly pathetic budget didn’t include buying another set of studded winter tires, so my brain started processing alternatives. I had heard that serious ice racers were making their own impressively-studded tires by running hundreds of bolts through their tires, and having some serious results. I got to researching the process and before I knew it I was rooting through a garbage tire bin and pulling out a set of very bald tires for my Subaru. A lucky find on Kijiji scored a bucket of cheap 5/16ths, 1-inch long bolts and nuts.

First of all I decided where to install the bolts. I used what was left of the tread on the tires to guide my placement and spacing and used a chevron shape. I marked this out with a paint pen.

Ideally the pattern of bolts should be staggered so that the next set of bolts doesn’t contact the ice in the same place as the set before it. I went for about 100-120 bolts per tire, but I have heard of people using up to 250 bolts per tire.

Next comes the drilling. So much drilling. If you’re going to do this, you’re going to get very cozy with your power drill. Wear gloves or suffer blisters.

After some trial and error, I found that it was best to use the smallest drill bit that you can get away with for the size of bolts you are using. The tighter the fit, the better the tire will hold air. I think I ended up using a ¼ drill bit for my 5/16 bolts, but the hole ends up much smaller than the drill bit due to the spread of the rubber. It should be very difficult to thread the bolts in - nearly impossible to start the bolt threading with bare hands.

I found that lots of pressure on the tire while drilling made for much faster work. It also saved my drill bits from burning up too quickly, which tends to happen when drilling at high speed through rubber. Still, the bits are really dulled by this.

With the holes drilled, the next step is to thread in the bolts. I set up a batch of bolts assembled with washers, put a socket on my drill, and went to town. With the power drill, you should be able to get the bolt to bite into the tiny hole in the rubber and pull itself through, kind of like a wood screw.

I have heard of people adding a urethane windshield sealer to the bolts at this stage to help the tires hold air. Given the time invested and amount of mess already involved in this task I opted not to do so.

With the bolts installed, washers and nuts were put on the outside. Again, the power drill is the way to go here. Turning all those bolts by hand would take approximately one billion years. I finish tightened them with a socket and a wrench to snug them down.

I then mounted the tires on wheels and filled them with air. To see just how badly they leak, I sprayed them with soapy water. Yup, they leak! Especially the first tire I drilled, before I learned to use the smallest drill bit I could. I used an impact wrench to really tighten up the worst-leaking bolts, which lessened the leaking a bit.

Filling the tires with about 16oz. each of tire Slime really slowed down the leaks - enough to get a day of fun out of them, anyway.

If one of the bolts comes loose the tire will deflate and be instantly useless. Since I used only regular nuts (instead of nylock nuts), to prevent loosening I tack weld the nuts and bolts. This was a terrible idea. After making 450+ tack welds, I would have gladly spent the extra $20 or so for the nylock nuts.

Next up, sharpening. If you’re getting your tires mounted by a shop, have them mounted up before sharpening them. The tire techs will appreciate not being stabbed while they work. Speaking of mounting, don’t worry about balancing these tires. You’d have a hard time getting them balanced with all that added steel on the tire, and for a little ice racing you won't notice an imbalance.

I have heard that the best way to sharpen the bolts is with a snowmobile track stud sharpener - a device that fits on a power drill and turns the bolts into a nice, sharp point, kind of like a pencil sharpener. I just used my angle grinder to cut the ends of the bolts on an angle, which created an interesting cornering characteristic that I'll cover later in this article.

The first day of testing showed amazing grip, but also showed a fault in my design. I left the bolts slightly too large and they would occasionally take a malicious stab at my rear fenders.

A coating of asphalt fender spray covered the scratches, and another session with the angle grinder minimized the length of the studs.

Next time out on the tires I was free of fender damage. I really got to play with the studs, and the grip they offer is phenomenal. I would compare them to driving on a hard-packed dirt road. Not quite the grip you’d get from asphalt, but so much more than you would expect to have on glare ice. I was hitting over 120kph on one section of the course, whereas other cars with regular tire studs were lucky to hit 70.

The angled cuts on the studs were made in only one direction, angled to give the tires more grip bias in the forward direction. This meant that I could accelerate like crazy, but the car would still slide very sideways in the corners. The technique I developed involved tossing the car into a slide, then getting back hard on the gas to pull the car forward into the turns, using the forward bite of the studs. It was very fun and satisfying, but very unlike driving on regular tires. A bolt sharpened to a point would probably have given more consistent traction in all directions.

A hidden benefit of the aggressive bite on the ice was the traction it created for all the other non-studded cars on the ice. On the lines that I was taking, the ice got chewed up and roughened so that there was a distinct increase in traction for the other cars. The downside is that for longer sessions, it would probably create some deep ruts.

So, was all the time invested worth it? Yes! Driving on ice on bolted tires is an incredible experience.

Here are the main points to take away from this:

1. It’s going to take time. Lots of time. The last tire went much faster than the first, but I think I averaged about 2-3 hours per tire.

2. Use the smallest diameter tires you can find to fit your car to leave extra room for the studs. Ideally, I would have used some 195/55R15 tires instead of 205/55R16. New tires with full tread depth would have been even worse than the bald ones I used.

3. Use the smallest drill bit you possibly can to make the holes. They will hold air for much longer this way. Still, they’re going to leak. Fill them up to 40psi before you leave and bring an air pump with you.

Disclaimer: I’m sure I don’t need to say this, but of course these aren’t for street use. Your local government really wouldn’t appreciate what these tires would do to their pavement. These are only for taking to the frozen lake in the back of your car, swapping over from street tires, and having fun. So much fun.