Formula One tyre

Formula One tyres play a significant role in the performance of a Formula One car. The tyres have undergone major 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 (50,000 miles), the tyres used in Formula One are built to last less than one race distance. The purpose of the tyre determines the compound of the rubber to be used. In 2005, tyre changes were disallowed in Formula One, therefore the compounds were harder as the tyres had to last the full race distance of around 300 km (200 miles). Tyre changes were re-instated in 2006, following the dramatic and highly political 2005 United States Grand Prix.

In 1998 grooved tyres were introduced with three grooves in the front tyres and four grooves in the rear tyres. Between 1999 and 2008, regulations required the tyres to feature 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 could be no wider than 355 mm (14 in) at the front and 380 mm (15 in) at the rear, and the maximum diameter was 660 mm (26 in), or 670 mm (26.4 in) for wet tyres. Slick tyres were reintroduced at the beginning of 2009, along with aerodynamic changes intended to shift the balance towards mechanical grip in an attempt to increase overtaking.

For 2007, 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 (referred to as the "prime" tyre) and is more durable but gives less grip, and the softer tyre (referred to as the "option" tyre) gives more grip but is less durable. Both compounds have to be used by each car during a race and the softer tyre had 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.

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