Tire Pressures 101

[turboduff]

Hello everyone

I am a newbie in Motorsport and I often visit nearby racetrack to watch races. I often see mechanics bleeding off the air from tires sometimes when the car comes into the pits, but I never realy knew how they do it.

Can anyone explain how the tire pressures work, how cold pressures are set and how mechanics control the hot pressures using bleed for contiousnly varying track and atmospheric temperatures?

[rscsr]

Hello everyone

I am a newbie in Motorsport and I often visit nearby racetrack to watch races. I often see mechanics bleeding off the air from tires sometimes when the car comes into the pits, but I never realy knew how they do it.

Can anyone explain how the tire pressures work, how cold pressures are set and how mechanics control the hot pressures using bleed for contiousnly varying track and atmospheric temperatures?

In essence you want a certain pressure when you are on the track. So you set it to a lower pressure (which you estimate from your target pressure) when the tyre is cold. Obviously everything heats up during a run and therefore you check the pressure and bleed it until you are on the target.
When you heat the tyre again, you are usually pretty close to your target pressure.

[turboduff]

And once when the tire reaches its target pressures it stabilises? If yes, for how long?

[rscsr]

And once when the tire reaches its target pressures it stabilises? If yes, for how long?

I don't think I quite understand what you mean.
But I try anyway.

The mass of air in the tyre is constant. Therefore its pressure depends only on its temperature.
The air gets heated due to surface temperature of the rubber (and the rim temperature). When you are on the track everything gets hotter until the temperatures stabilize (this means, that the temperatures only depend on the position on the track, and not how long the run is anymore. Basically you lose temperature on the straights and increase the temperatures in the corners)
Of course the temperature you lose depends on the grip available, slip, how much rubber is left, contact area, ...

[turboduff]

Okay now I understood, Thanks mate