Racing Tire Prep Information From American Racer®
Tire preparation could be a web site all onof it’s own. Different tires and different track surfaces usually result in different tire preparations.
Asphalt Racing Tire Prep:
It is highly recommended that asphalt tires be hot lapped before racing. Hot lapping will set the ultimate size of the tire and allow you to set your stagger with more confidence. If your asphalt track was recently resurfaced we recommend at least one and preferably two heat cycles (hot lap sessions) before the tires are used in a feature. Recently resurfaced asphalt tracks often have sharp edged aggregate and tend to blister tires. One or two heat cycles will reduce the tendency to blister.
Asphalt tires can be stretched to help achieve stagger requirements. After the bead has been set the tire can be aired up to ca 40 psi and set out in the sun. As the tire heats up in the sun it will stretch. If you use bleeder valves during the race, the stretched tire may shrink again.
In a similar way, asphalt tires can be shrunk. Get a lot of heat into the tire during a hot lap session and deflate the tire immediately. As the nylon cords cool, they will shrink. A word or warning, jack the car up before the tire is deflated.
Dirt Track Racing Tire Prep
Everyone has their own little tricks of the trade when it comes to preparing dirt track tires. There are some fundamental things to remember.
Sipes- Sipes create heat. The only reason to sipe a tire is to generate “wiggle” in the tread. The siped surfaces, ie the inside of the cut, rub and wiggle against each other and heat is generated.
Grooves- Grooves do two separate and sometime contrary things to tires. Grooves reduce heat. Heat escapes from the surfaces created by the grooves. One large block of rubber will be hotter in equal service to two smaller blocks that sum to the same amount of rubber. The smaller blocks have more total surface area to shed heat and the distance to a surface is shorter. Grooves also create edges. More edges generally help on a slick, non-abrasive track. Ironically, slick, non-abrasive tracks don’t tend to generate much heat in a tire. On an abrasive track a racer may groove his/her tires to shed heat. On a non-abrasive track a racer may groove the tires for edges and then sipe them like crazy to try to get heat.
