Tyres

Formula One tyres play a significant role in the performance of a Formula One car. The tyres have undergone significant changes throughout the history of Formula One, with different manufacturers and specifications used in the sport.Formula One tyres bear only a superficial resemblance to a normal road tyre. Whereas the latter has a useful life of up to 80,000 km, the tyres used in Formula One are built to last less than one race distance. This is determined by the compound of the rubber used. In 2005, tyre changes were disallowed in Formula One, the compound was harder as the tyres has to last the full race distance (around 300 km). Tyre changes were re-instated in 2006, following the dramatic and highly political 2005 United States Grand Prix (see below).
For pre-2009 regulation, the tyres featured a minimum of four grooves in them, with the intention of slowing the cars down (a slick tyre, with no indentations, is best in dry conditions). They can be no wider than 355 mm and 380 mm at the front and rear respectively and maximum diameter is 660 mm (670 mm for wet tyre).[1] Slick tyres were reintroduced at the beginning of the 2009 season in an attempt to increase overtaking.
For the 2007 season Bridgestone became the sole tyre supplier in Formula One with the withdrawal of Michelin, and introduced four compounds of tyre, two of which are made available at each race. The harder tyre is more durable but gives less grip, and the softer tyre gives more grip but is less durable. Both compounds have to be used by each car during a race and the softer tyre has a painted white stripe in the second groove to distinguish between compounds. This was introduced after the first race of the season when confusion occurred because a small dot was put on the sidewall of the tyre, instead of the white stripe.
Upon the reintroduction of slicks in 2009, the sidewalls of the softer tyres were painted green to indicate the difference in compound, as there were no longer any grooves in tyres. Each team must use each specification during the race, unless wet or intermediate tyres are used during the race, in which case this rule no longer applies.In extremely wet weather, such as that seen in the 2007 European Grand Prix, the F1 cars are unable to keep up with the Safety Car in deep standing water due to the risk of aquaplaning.