Introduction
For the 2008 season Bridgestone supplies motorcycle tyres to a total of seven MotoGP teams, five manufacturers and 12 riders. In contrast to other racing series in which Bridgestone is the sole tyre supplier to the entire field, the MotoGP department has to provide tyres to its teams that not only beat the competition, but that also prove versatile enough to give each rider the flexibility to adapt to their own unique style.
Structure
The tread of a MotoGP tyre is rounded in shape to create the largest possible contact patch with the road (when leaning at angles of up to 65°). The tyre construction is designed to be durable against severe braking and acceleration forces, whilst providing riders with enough feel to sense the tyre’s performance limit.
Bead - The bead acts as an anchor to hold the tyre on to the rim. The rubberized bead is stretched over the rim to ensure that the two components are tightly secured together.
Inner liner - Positioned below the carcass, the liner ensures the tyre is air tight. The inner liner is produced from a specifically formulated rubber compound.
Carcass - The carcass ensures that the tyres are able to support the mass of the motorcycle and provides the tyre with additional stability.
Tread - The tread is formed from rubber compound and generates grip for the tyre through hysteresis (the absorption of energy during the deformation of the rubber) and adhesion. The tread on a MotoGP tyre is designed so the performance level remains as consistent as possible during the race.
Sidewall - A MotoGP tyre's sidewall copes with high cornering forces and provides stability of the MotoGP machine.
Bead - The belts are a core component within Bridgestone motorcycle tyres as they prevent the tyre from deforming, due to the hoop shape of the belt. The belts may be steel, polyamide, nylon, polyester or other materials and are arranged in a secret combination to provide strength, additional side force and puncture resistance.
Compound
For the 2008 season each rider will have available to them Dry Slick and Wet Weather Tyres.
Dry Weather Tyres - Within MotoGP all riders use dry slick tyres. A slick tyre is a treadless tyre providing maximum contact with the track surface and providing superior traction on dry tracks. A range of different compounds is available to riders at each event.
Wet Weather Tyres - A MotoGP wet tyre is defined as having a land-to-sea ratio of at least 20% overall, and a minimum ratio of 7% in each third of the section profile. Any tyre with a land-to-sea ratio of less than 20% will be deemed slick. Wet tyres may be moulded or hand cut, but each groove must have a minimum depth of three millimetres over 90% of its length.
Regulations
Regulations are the rules or conditions that govern procedure. The codes and statutes for the MotoGP World Championship are drawn up by FIM, the governing body of motorcycle sport at a world level.
Dry Slick Regulations
During practice, warm up and the race itself, a maximum of 40 slick tyres (18 front tyres, 22 rear tyres) may be used. When a tyre manufacturer who is not subject to the 40-tyre limitation at the beginning of the season achieves two MotoGP wins in dry conditions during that season, it will become subject to the restriction at the third event following the one where the second win was achieved.
Wet and Slick Regulations
Wet tyres are not subject to supply restriction. Tyre Allocation Regulations In the case of an interrupted race, a rider must use tyres from his allocation of marked tyres for the restarted race.