Supplier claims Silverstone curbs also at fault in F1 tire controversy

Formula One teams contributed to the dramatic blowouts at Sunday's British Grand Prix by mounting rear tires the wrong way around and running them with low pressures, supplier Pirelli said on Tuesday.

Rejecting any suggestion its product was dangerous, the Italian company said in a statement it would bring stronger rear tires to this weekend's race in Germany to allay any safety fears and introduce a new range in Hungary at the end of the month.

Pirelli said some teams had deliberately put tires intended for the right rear of the car on the left, had run them at lower pressures than recommended by the manufacturer and used extreme cambers for performance advantage.

However, it shouldered some of the blame for these practices. "Mounting the tires the wrong way round is a practice that was nonetheless underestimated by everybody: above all Pirelli, which did not forbid this," said the statement.

Pirelli found the curbs at fast corners, and specifically turn four of the Silverstone circuit, were also "particularly aggressive".

Four drivers suffered high-speed rear tire blowouts at Silverstone - Lewis Hamilton (Mercedes), Felipe Massa (Ferrari), Jean-Eric Vergne (Toro Rosso) and Sergio Perez (McLaren).

The debris from the exploding tires was flung up into the path of cars behind, with Ferrari's Fernando Alonso having one near-miss. Fears about the drivers' safety plunged the sport into crisis with talk of a possible driver boycott.

Pirelli said the rears to be used at the Nuerburgring on Sunday would feature inner belts made of Kevlar, a reinforced fiber that was a feature of last year's tires, beneath the tread instead of the steel used so far this season.

Its 2013 tires have an 'asymmetric' structure which means that they are not designed to be interchangeable but some teams struggling with high degradation have improved performance by swapping them around.

"The sidewalls are designed in such a way to deal with specific loads on the internal and external sides of the tire. So swapping the tires round has an effect on how they work in certain conditions," said Pirelli.

"In particular, the external part is designed to cope with the very high loads that are generated while cornering at a circuit as demanding as Silverstone, with its rapid left-hand bends and some curbs that are particularly aggressive."

Under-inflating the tires can also bring a competitive advantage but puts more stress on them.

Pirelli said that, because of the potential danger, it had asked governing FIA for a technical official to make sure cambers and pressures complied with set parameters in future.

It will also be forbidden to swap the new rears for Germany, since they too are asymmetric. The front tires remain unaltered.

The tires to be used at the Nuerburgring had been made originally for teams to try out in Canada last month. But they were not used due to bad weather and opposition from Ferrari, Force India and Lotus whose cars were easier on the tires and who feared giving up an advantage.

Those tires, to be introduced in Hungary at the end of July, will have a symmetrical structure with the 2013 compounds.

(China Daily 07/04/2013 page23)