Friday, May 30, 2008

Understanding F1 tyres

As the cars’ only contact area with the track surface, tyres obviously play an enormously important role in the performance of the machines. So critical, in fact, that the sport’s governing body invariably uses limitations on the specification of the tyres as the key way of controlling the performance of the cars. The limits for dry-weather tyres are currently those of width and tread groove.
  • Width: The front tyres must be between 12 and 15 inches (305–381mm) and the rear tyres between 14 and 15 inches (356–381mm). The back tyres can be wider than the front because the back has more work to do. The weight distribution of the car is rearward-biased, because that’s where most of the mechanical components are. Furthermore, the rear tyres are transferring the engine’s power to the road.
  • Tread groove: Four grooves must run through the circumference of the tyre. The shape and depth of these grooves is also specified by the regulations. The regulations for a wet tyre specify contact area rather than tread pattern or shape.
Formula One tyres grip the track far better than those of any road car could, but this performance comes at the expense of durability. However, a set of tyres on a Formula One car does not need to last any more than the length of a race and more often than not, even less.
Both grip and durability are largely determined by a tyre’s compound, the complex mix of the constituent chemical parts that comprise the material the tyre’s made from. The softer the compound, the better gripping but less durable the tyre. Different circuits place different demands on a tyre, according to the nature of the track surface and the design of the course. Tyre manufacturers come up with compounds tailor-made to each track. The other critical aspect of a tyre’s design is its construction, the way in which its carcass is designed. The stiffer the construction, the greater the load the tyre can withstand and, therefore, the softer the compound can be. A Formula One tyre is very temperature-sensitive. It has virtually no grip at all below its designed operating temperature and would therefore be lethally dangerous if used on the road. Getting the tyre up to temperature requires braking and cornering hard enough that only an accomplished racing driver is able to do it.

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