NASCAR cars use radial tires just like the ones on a normal road car. However, that’s by far the only similarity. A NASCAR car runs under very different conditions than road cars do and therefore, NASCAR’s tires have special requirements. One of those requirements is to remain stable at extremely high temperatures, and this is how the teams ensure that.
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Most of the teams use nitrogen in their tires instead of plain air. Nitrogen, in its compressed state, holds less moisture than air. Therefore, when the tire heats up due to the friction between the rubber and the track, the moisture vaporizes and causes the pressure to shoot up. However, tires blowing out at 200mph can be extremely dangerous. Hence, the race teams blow less nitrogen than required in the tires, which is about 50 PSI, and that increases by up to 25 PSI, as the car runs on the asphalt and gains temperature. Thus, the relatively flat tire blows up, regaining its inflated shape.
However, not all four tires need this adjustment. A Joe Gibbs Racing video explained, “It is only on the left side. Right sides are inflated like normal. It helps with grip on a short track.”
Even a minuscule change in the tire pressure can radically change the handling of the car. That’s exactly why the teams often resort to this ingenious adjustment.
How are NASCAR tires special?
Dual liners
On racetracks that are more than a mile long, NASCAR tires use tires that contain an extra inner lining. In simpler words, there is a second tire inside the first one, which is right next to the rim and has a separate air supply. So, even if the outer lining of the tire, which is in contact with the racetrack, blows up, the inner tire will remain intact and that will help the driver control the car as it comes to a halt.
Track compounds
NASCAR decides what compound will go into making the tires. Different compounds are used for different tracks. A softer compound provides an additional grip on the track, but the downside is that it wears off easily. On the other hand, a harder compound lasts longer, but the grip it provides is significantly less. A lot goes into selecting these compounds; track type, banking, tightness of the turns, and number of turns, all work together in determining the same. Therefore, NASCAR and Goodyear work together to choose which compound to use for each track.
Bald tires
A NASCAR tire does not have ridges on its outer surface like a generic tire would do. However, this unusual design is made on purpose. Indeed, tires with tread help provide grip during wet track conditions, but when the track is bone dry, having the entire surface area of the tire touching the ground is optimal, as they generate more traction. This is why NASCAR stops its races when it rains.
