Formula 1 tyres don't have air in them like normal car tyres. Most racing tyres have nitrogen in the tyres because nitrogen has a more consistent pressure compared to normal air. Air typically contains varying amounts of water vapour in it, which affects its expansion and contraction as a function of temperature, making the tyre pressure unpredictable. To avoid this, the tyres used in Formula 1 cars are free of water vapour, as a 20% Tyre pressure drop reduces tyre life by 15%. During the race the tyres lose weight! Each tyre loses about 0.5 kg in weight due to wear.
Formula One tyre for dry surfaces measures 660 mm in external diameter and 350 mm wide, containing four longitudinal grooves of at least 2.5 mm imposed by the Depth Regulations. These grooves are symmetrically placed from the centre of the tyre tread and spaced 50 mm apart.The dry surface tyre is a completely new concept, introduced to Formula 1 with the sole aim of reducing the size of the ground contact area, i.e. the surface which ensures grip, resulting from the contact of the rubber compound and track. The aim of the regulations is to reduce the speed of the cars on corners. Their life varies between 80km to 200km depending on the type of the compound used and temperature.
Intermediate tyres are used under fine to moderate rain to ensure maximum grip, when the use of Wet Tyres is not deemed necessary.They have a special role on a drying track, they must evacuate the film of water but also remain competitive on the dry without deteriorating too much. The life of a Intermediate Tyre is extremely variable depending on the track temperature.
Wet tyres must evacuate the water that infiltrates between the tyre contact area and the track. If the film is great, then the tyre loses grip and this results in aquaplaning. These tyres can be used for the entire length of the race and from temperatures between 30 degree Centigrade and 50 degree centigrade.
