Pirelli confident that softer compounds won't be an issue for Anniversary race


In the wake of Pirelli's investigation into the tyre failures suffered by both Mercedes drivers and Carlos Sainz at the end of last week's British Grand Prix, it was the news that the Italian manufacturer is persevering with its plan to use softer compounds this weekend that raised eyebrows.

In the wake of the failures to hardest tyres in the range, in the aftermath of last Sunday's failures and the issues faced by various other drivers, it was assumed that Pirelli might revise its plans for this weekend's Anniversary Grand Prix.

However, other than increasing tyre pressures, the Italian manufacturer is relying on common sense from the teams.

"The investigation says that the cause of the initial loss of pressure and then the deflation was the level of stress on the tyre, on the construction of the tyre," said Mario Isola in a media conference following Pirelli's investigation of last Sunday's failures.

"For that reason the action we are taking for the next race is to increase the pressure," he continued, "because obviously it is the pressure that is helping the construction.

"And we keep the same compounds, C2, C3 and C4, that have been already decided a few weeks ago," he added. "The tread compound is not affecting in any way what happened on the tyres.

"I don't want to use the words 'perfect storm', because I don't like it," he admitted, "but the fact that the safety car was out on lap 12, obviously was pushing everybody to change on lap 12. In a normal situation, a normal strategy was to change for cars that were targeting a one stop strategy at lap 18-20.

"Consider also that when you follow a safety car the pressure is going down, and then obviously at the restart of the safety car, there is a period in which the pressure grows

"At the restart of the safety car you have a very quick corner, with a lot of energy that is going into the tyre. We usually consider that in our estimation, when we give the prescriptions, we consider all that. And it was confirmed from telemetry data that the level of energy was very, very high.

"So the safety car plus the long stint plus the fact that the construction with less tread is less protected caused an initial loss of pressure, and the loss of pressure leads to a deflation.

"If you look at the tyres they had both sidewalls still in place in the right position, and the tread ring was broken, that is the typical situation when you run the tyre flat."

Looking ahead to this weekend, he said: "I believe that because we are going with one step softer compounds the length of the stint will be shorter by definition because the compounds are softer.

"Consider that the medium compound that will be the hard for this weekend, the only one that was running 36 laps was Grosjean, and the tyres were completely finished. So I struggle to believe that they can run more than 30-something laps next weekend."

Asked about the cuts that many drivers experienced with their tyres, he said: "It is true that we recorded a high number of cuts, in some cases they were superficial, in some cases they were quite deep.

"The high number of cuts was recorded especially on the tyres from the second stint," he continued. "I believe that the pieces of the front wing lost by Kimi Raikkonen was the main cause of the cuts on the tyres.

"We had one tyre, if I remember well it was the front left from Latifi, with a puncture. The tyre was still losing air when he was coming back to parc ferme.

"I confirm that there was debris on track, I confirm we found some cuts. Also from the tyres used in the first stint, probably from the accident of Kvyat. But I think we came to the conclusion that the cuts were not responsible for what happened to the tyres of Mercedes and Carlos Sainz.

"It is clear with a high level of wear most of the tyres were close to 100% wear, without rubber on the tread, that is exposing the construction, the construction is less protected, and any impact on the construction has a different effect. And also any piece of debris is more dangerous, because it can cut the construction, and therefore cause a failure.

"But to tell you if the cuts on Max's tyre were big enough to stop him without an additional pit stop is difficult to say."

In terms of Kvyat's tyre, Isola confirmed that the exact cause is still under investigation.

"Kvyat's tyre is obviously a completely different situation," he said, "probably a slow puncture, but again we want to investigate deeply the tyre.

"It is going to Milan because it was not possible to understand exactly what happened on that tyre, it is probably something that is not related to the tyre or is a slow puncture, the most probable conclusion is this one.

"The tyre is not in great condition, as you can imagine, it's quite destroyed, but thanks to our laboratory we can do microscopic analysis and go inside elements of the tyre and have more careful analysis, so I'm confident that we can find the reason.

"I'm not 100% sure that it was a tyre failure," he admitted, "that's the important thing to explain. The tyre is broken, for sure, and we have to understand because sometimes, for example - and don't take this as an assumption - you have a rim that is broken, and if the rim is broken you lose air immediately, it looks like a tyre failure but it's not a tyre failure.

"So we need to be 100 per cent sure and that's why the tyre is travelling to Milan."

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Published: 05/08/2020
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