Racing Tire Siping, Grooving, and Needling
Traction. The one thing we want, and the one thing that is affected by every single thing we do to our cars. It all comes down to the tires. One thing we can do, legally, to our tires is groove them and sipe them as needed.
Siping is making a razor thin cut into the tread blocks of your tire. These sipes provide additional gripping edges which can increase traction. One major thing to keep in mind is that while grooves can, and often do extend the full depth of the tread block, don’t do that with your siping. This can result in chunks of your tires actually tearing out, and you becoming very good friends with your tire supplier. It is recommended to never go beyond ½ the depth of the tread block. On a tire made of a harder compound, these sipes will help to keep the tire from “glazing” or sealing over. The sipes isolate heat into small channels allowing air to flow between them, thereby dispersing the heat and cooling the tire. Shop all our heated and non-heated tire sipers here.
Grooving is exactly what it sounds like. You trim out a narrow strip of rubber from your tire to channel all the mud and dirt and debris to the outer edge, increasing your contact patch, and thus, your traction. There is most definitely an art to this, however. You can talk to five different people and get ten different patterns that they say are the best to groove into your tires. Horizontal, vertical, diagonal...heck you can even carve diamonds into the tread if it works for the particular track you are running at that point in time. Most tire groovers use V-shaped blades that are heated using electricity to provide a quick, clean and precise cut. Blades typically range from 1/32” to 1/2” wide and can have either a flat bottom or round bottom, depending on the type of groove you want to make.
Another technique that has recently come back into use is needling. This punches small holes into the tread of the tire, and is supposed to act in a manner similar to siping. By creating friction on the tire you can get it to temp faster, and by increasing the surface area once at temperature, it is supposed to dissipate heat more effectively than a non-needled tire.
The tools to do this are not going to cost you a fortune. In fact, this Tire Groover retails for about $75. And by simply flipping the blade over, you can also sipe your tires.
A commonly held belief that our techs hear regularly is that siping across the tread of a tire will aid in putting heat into the tire, where going around the tire will help dissipate heat.
Now, just like was mentioned earlier each track will present differently, meaning you may need to keep a running log of what works best for the track you are running on that particular night. This way, when the circuit brings you back to that track again, you already have a fairly good idea of what pattern will do the trick. Just like anything else, it takes time to find what works best.
As always, refer to the rules to be sure you aren't breaking any.