Why Do Race Cars Heat Their Tires Before a Race?

[JBeans]

Why exactly do race cars have their tires heated before a race?

 

[Cyrus]

I think they do it so that they become warm. This enables the rubber to become "sticky" and give better traction. For drag cars, I know that they burn out their tires, and for stock cars, they do zig zags while they are restricted to following the pace car because the race has not started yet, or the race has been paused to clear up a reck.

 

[brewnog]

Indeed. Warm tyres are stickier. It's to do with the softening of the polymers (polyisoprene? anyone?) with temperature, - one of the reasons winter tyres are recommended for cold weather use is not so much to do with grip (although tread patterns are optimised for use in wetter weather) as with the increased friction the different compound gives at lower temperatures.

 

[LunchBox]

While they are stickier (and that is part of the reason), the primary reason for heating the tires is to maintain a nearly constant tire pressure from when the tire goes on the car to when it comes off some hundred miles later.

Pit crews have gotten so good at making control adjustments to a racecar that they know down to a quarter or eigth of a psi the optimal pressure for the weather, track conditions, and driving style that will give their driver the best performance from the vehicle. This knowledge would be useless if the pressure changed by a few psi from when the tire was put on, to when it was up to racing temperature (from friction with the track surface).

Note that the same applies for your car. If you look, most commercial tires say something along the lines of "inflate COLD to 35 psi". That's because the tire optimally performs at 38-42 psi which is the pressure that the tire will achieve after the air inside has been heated due to driving.

Believe it or not, NASCAR is not necessarily a redneck sport anymore...

Cheers...

 

[Cyrus]

While they are stickier (and that is part of the reason), the primary reason for heating the tires is to maintain a nearly constant tire pressure from when the tire goes on the car to when it comes off some hundred miles later.

I never knew that, learn something every day on here.

Yeah, now only the renecks watch, LOL. I guess I am a redneck, eh, I can live with that.

 

[brewnog]

Pressure eh, cunning!