Pirelli tires experience high-speed extremes in Monza
At last weekend’s Italian Grand Prix in Monza, Red Bull driver Daniel Ricciardo – the winner of three grands prix this year – reached 362.1 kph (while slipstreaming) on the main straight: the highest top speed that will be clocked in 2014. At the speed Ricciardo recorded, the wheel is rotating around 2800 times every minute, or just under 50 times every second.
These extreme speeds have a profound effect on the tires. At full speed, which is frequently the case during a lap of Monza, a Formula One tire is often subjected to a downforce load up to 1000 kilograms. Another important aspect is that the high speeds generate a huge centrifugal force on the tire itself. Because of these loads, the footprint of the tire increases and the part of the tire against the ground is subject to a lot of deformation, as shown in illustration 1 below. The structure of the tire has to be incredibly strong and elastic to cope with this constant flexing. At the same time, the upper section of the tire (which is not in contact with the ground – illustration 2) is subjected to a big centrifugal force, but despite this the shape of the tire does not change much: stretching by just 1%. This is due to the low weight and extremely high stiffness of the materials developed by Pirelli for Formula One.
Figure 2: Beyond 350kph, the highest part of the tire only changes shape by 1%, despite being subject to an enormous centrifugal force.
The F1 tires are designed precisely with these extreme forces in mind: during laboratory testing, before they even see a race track, the tires are exposed to higher loads and forces than they would normally experience, and accelerated to speeds of up to 450kph. Not only that, but they are also fired into solid surfaces at speeds in excess of 250kph: simulating the impacts with kerbs for which Monza is also famed. So while the forces at work on the tires in Monza are almost unimaginable, Pirelli’s tires are specifically created to rise to the biggest challenges and highest levels of overall performance seen in world motorsport.
Similar speeds can be put through Pirelli’s Ultra High Performance tires for the road by the world’s top supercars: most of which use P Zero tires as original equipment. Not only does the road-going product share a name with its Formula One equivalent, but also much of the technology and design processes that make Pirelli’s tires unique.