F1’s tyre supplier had previously been cryptic in suggesting in a statement that ‘running conditions’ had been behind the tyre failures suffered by Max Verstappen and Lance Stroll in Baku, it has now elaborated further on what triggered the blowouts.
While Pirelli confirmed that both Red Bull and Aston Martin had followed the regulations with the minimum starting pressures and maximum blanket temperatures, it says that things deviated from what it expected once the cars were running.
Pirelli normally sets a starting pressure based on an expectation that the Psi will then raise further once the tyres are running out on track.
However, it appears that the tyres on Aston Martin and Red Bull did not experience such a raise in pressure in Baku and were therefore running at a lower level than Pirelli anticipated.
By running below the pressure that Pirelli expected, it meant the standing waves being caused by the high-speed Baku corners were enough to trigger the failure on the inside shoulders of Verstappen and Stroll’s left rear tyres.
Speaking to media at the French Grand Prix, Pirelli’s head of F1 and car racing Mario Isola confirmed that both teams were running with tyres outside of what Pirelli had expected.
“What happened in Baku is simply that the running conditions expected were different compared to the actual running conditions – and that created the failure,” he said.
“When you have a lot of energy going into the tyres, with the pressure that is lower compared to the expectation, the result is that on the sidewall you have what we call standing waves.
“Standing waves are putting a lot of energy into the inside shoulder of the tyre. And, at a certain point, the tyre breaks. That is what happened, and the reason why we had this situation in Baku.”
Isola said that the issue was not totally down to the tyre pressures at those two teams being below what was expected.
Another contributing factor was that Pirelli’s predictions for car performance over the weekend, based on data that teams had supplied, were not in line with how they really fared out on track.
“When we prepare the prescriptions [for minimum pressure], we receive the simulations and we consider margins,” he said.
“The expected loads, the downforce or the speed, are simulated, so it is not exactly the value that we find on track. And in this case in Baku, we also found some parameters that were not exactly what we found on track.”
Max Verstappen, Red Bull Racing, climbs out of his car after crashing out from the lead
Photo by: Steve Etherington / Motorsport Images
He added: “We assume that they are running at a certain pressure, and a certain camber. And with a margin on it, of course, we run in a condition that is OK for the tyre.
“In that case, we didn’t achieve these conditions, not because teams were doing something against the regulations, but because they were looking as usual for performance, and that created a different scenario to what we were expecting. And the different scenario was that mainly the tyres were running at a lower pressure compared to expectation.”
Isola said that the teams had not done anything against the regulations because there is no minimum running pressure that needs to be adhered to.
However, that is changing for next year when teams must run with a standard pressure sensor as part of F1’s new rules era.
“If the regulation is not written that there is a running pressure that you have to respect, I cannot say that they were doing something against the regulation in their search of more performance,” continued Isola.
“If they respect the starting pressure, they are complying with the regulation. If the same happens next year when we, with the standard sensor, impose a running pressure, in that case they are against the regulations. But this is not the case this year.”
Isola said it was not really a surprise that teams were pushing the margins on tyre pressures, as he suggested the spread between teams on running pressures in Baku was more than one Psi.
“Each team is looking for performance,” he said. “They are here racing, they are not here just to cruise on track. And that means that, looking for performance, we know that if you go with a bit lower pressure, you get some performance.”
Although there have been suspicions about teams playing around with pressures in recent races, Isola said Baku was the first time that it had been picked up in such a way.
“We check every time the running parameters when we receive the telemetry data from the race,” he said.
“We check everything on all the teams, of course, and also because it’s an indication for the following race and its prescription, so we use the data.”