Spanish Grand Prix 2013: Pirelli pinpoints reason for di Resta failure
11 May 2013
Pirelli has confirmed that the method of construction used on its 2013-spec F1 tyres played a major part in the way Paul di Resta's left rear failed during Friday practice at the Spanish Grand Prix.
The Scot was seven laps into a long run on the medium compound being supplied as the 'option' tyre this weekend when the tread belt came away. Although the tyre remained inflated, di Resta was advised to pull over on the main straight, ending his session earlier than expected.
Pirelli, having seen other failures on the same compound during the recent Bahrain Grand Prix weekend, investigated the issue overnight, with Paul Hembery emerging to explain its findings ahead of the third and final practice session in Barcelona.
“It's similar to the other tyres we've seen [fail] this season,” he confirmed in an interview with the BBC, “We've made the move to put high tensile steel into the belt [for 2013] so, when you pick up debris, it doesn't penetrate the belt. [As a result], the weak point becomes the tread so, if you get a cut, it overheats the tread and it comes away, as you've seen.
“Last year, it would have deflated the tyre - it would have gone on through and the car would have come in with the tyre on the rim. So we've changed the mode of failure which, from one point of view, you could say is safer because [the tyre] stays inflated, but, from a tyre manufacturer's point of view, it looks more dramatic because I'm sure people watching will think that it's just coming away by chance, when it's not. There's always a reason for it.
“We've used 10,000 tyres this season, we've seen four cuts of that type and it has been the same in each case. Because you can't penetrate the belt pack , it heats up and comes away. You could ask if that is worse or better, I don't know. You're damned if you do, damned if you don't, maybe.”
Hembery's comments come in the wake of drivers beginning to express their fears over the spate of failures, which affected both Lewis Hamilton and Felipe Massa to major effect in Bahrain.
"It's a big concern for all of us,” McLaren's Sergio Perez claimed, “You see two or three cars every weekend having this problem. There can be a really serious accident."
While Hembery continued to insist that the number of failures was no different to previous seasons, he conceded that there may be a need to alter the construction of the tyre in a bid to allay those fears, even though that course of action would have its own consequences.
"We would have to look at changing some parts of the structure, which is something we can do," he explained to sportinglife.com, "But we would need to balance that with what impact it might have on the teams because they have a lot of data that's based on this year's structure which influences aerodynamics.
"Also there is a lack of testing. Some of the solutions we might need would need some more extensive testing, so we are caught in between a bit of a rock and a hard place.
"But we do take these things seriously. We're looking at it to see if we can change this mode of failure, the visibility of it and turn it into something that is less dramatic from a visual point of view.”