If you're a fan of dirt track racing, I'm sure you have heard a lot of terms relating to tires. You probably even have a basic idea what each term means, but do you know how all those things work together, why teams do them, or when they happen? No? Well then, read on.
- Siping - Siping is a technique first patented in the 1920's by a man named John Sipe who came up with the idea of putting razor cuts in his shoes to give him better traction. When applying this technique to a dirt tire, siping will do many things. First, this will help the tire build heat quicker which will help the tire "fire" better. Siping will also dissipate heat when the tire gets to operating temperature and the sipes open up.
- Grooving - Grooving will help channel the dirt out the tire to help maintain a good contact patch between the tire and track surface--just like the grooves in your street tire which help keep your car from hydroplaning. Grooving will also create more edges for better traction or grip. Unlike siping in which you should go no deeper than 1/2 the depth of the tread block, grooving is typically the full depth of the tread block.
- Sealing Over - Drivers talk about their tires “sealing over” or getting “glazed”. No one knows exactly what is happening but one theory is that the heating of the tire during a race liquifies resins in the rubber compounds. These resins work to the surface and result in a shiny, glazed look and a slicker surface if the tire cools off during a caution or between races.
- Grinding - A disc grinder is used on the surface of the tire. Grinding removes the microscopic layer of sealed rubber (described in 'Sealing Over') and mechanically roughs up the smoothed tread blocks to give more bite.
- Blistering - Blisters occur when the tread overheats, which leads to the creation of air bubbles inside the tread and causes it to lift.
- Chunking - Loss of chunks of the tire tread during racing occurs when overheating and blistering is extreme enough to cause pieces of the tread to break away from the tire.
Check out the two articles below to learn more about how all these tire terms are related and get some insight from experts about tire temperature goals and how to read them, what you can learn from your tires after a race, why you should wash your tires between races, and other interesting tips!