Tyre failure caused Baku blowouts — not debris, says Pirelli


A sudden break in the tyres of Max Verstappen and Lance Stroll caused their high-speed crashes in Baku — and tyre pressure or temperature could be to blame, says Pirelli

Verstappen kick

A left-rear tyre failure pitched Verstappen out at 200mph

Clive Rose/Getty Images

The tyre blowouts that pitched Lance Stroll and Max Verstappen into the wall at more than 200mph were the result of a break in their tyres, Pirelli has said after an investigation into the Azerbaijan Grand Prix crashes.

It has rowed back from its initial assessment that on-track debris was to blame, saying that there is evidence that a circular break on the inner sidewall of the left rear tyres caused them to suddenly fail without warning.

The cause was not a defect, Pirelli says, but the “running conditions” of the tyre, inferring that teams had been racing tyres that were outside the temperature or pressure operating requirements

In a statement, Pirelli said that teams had complied with these limits before the tyres were fitted — as required to do.

It has announced a new set of protocols to monitor the operating conditions at this weekend’s French Grand Prix.

Teams have been suspected of pushing the boundaries of the tyre requirements, in particular by allowing the tyre temperature to drop after measuring the pressure, which could lead to cars leaving the pitlane with tyres at a lower pressure than required — with potential performance benefits.

Red Bull said that it always complied with Pirelli’s requirements.

“We have worked closely with Pirelli and the FIA during their investigation into Max’s tyre failure on lap 47 of the Azerbaijan Grand Prix and can confirm that no car fault was found,” said Red Bull

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“We adhered to Pirelli’s tyre parameters at all times and will continue to follow their guidance. We are grateful that following the weekend’s high speed impacts no drivers were injured.”

Pirelli said that it had examined the tyres used by Verstappen and Stroll as well as others in the race, some which were run for longer than those that failed.

“The process established that there was no production or quality defect on any of the tyres; nor was there any sign of fatigue or delamination,” said Pirelli.

“The causes of the two left-rear tyre failures on the Aston Martin and Red Bull cars have been clearly identified. In each case, this was down to a circumferential break on the inner sidewall, which can be related to the running conditions of the tyre, in spite of the prescribed starting parameters (minimum pressure and maximum blanket temperature) having been followed.

“As a result of this analysis, Pirelli have submitted their report to the FIA and the Teams. The FIA and Pirelli have agreed a new set of the protocols, including an upgraded technical directive already distributed, for monitoring operating conditions during a race weekend and they will consider any other appropriate actions.”