The FIA had been dragging its heels in making a decision on this, to the extent that the top F1 teams, who have already begun planning next year’s cars, have had to use data from the current Bridgestone tires as a basis for their plans. The delay had been caused because the FIA and Pirelli hadn’t been able to see eye-to-eye on tire specs. Pirelli wanted to create a low profile tire, of the sort now generally seen on sports, GT and prototype cars. Pirelli’s rationale was that this type of tire was more relevant to their tire designs for road cars. Pirelli had also wanted to invoice individual teams for their use of tires, a practice which apparently is not currently in place with Bridgestone.
A statement released by the FIA said, however, that, “Pirelli has been selected as the single tire supplier for the FIA Formula One World Championship for a period of three years, commencing in 2011. The sole supplier will undertake to strictly respect the sporting and technical regulations implemented by the FIA.”
In other words, if Pirelli wants to supply Formula 1 with tires, the tires will be built according to FIA specs, not according to Pirelli’s.
Reducing the profile of tires, while increasing the diameter of wheel rims, would dramatically change the overall suspension dynamics of F1 cars. Much of the shock absorption of an F1 car comes from the flex of tire walls, rather than the suspension arm assembly. Suspension arms are made of carbon fiber, and are relatively rigid compared to the tire walls. Reducing tire wall dimensions would necessitate redesigning the suspension arms as well.