Tire pressure

From Trackpedia

This is basically the pressure inside your tires. There are usually two tire pressures that are important, cold and hot. You measure cold before driving the car at all. Hot should be measured as fast as possible when you bring the car off the track.

Typically on hot days, you set the cold pressure in the paddock to the correct setting. This depends on the car, tire type, weather and you. When you finish a session then you release pressure down to the maximum hot pressure you want to see. Further sessions that day usually also require more air to be released as the air and track temperatures rise and you typically get faster through out the day.

Tire pressure can have a huge impact on the handling of the car and how long the tires will last. Incorrect tire pressures can even cause the tire to fail or blow out.