Formula 1 tyre supplier Pirelli says it will undertake a full investigation into the failures suffered in Azerbaijan, reckoning debris may be to blame, and labelled Lewis Hamilton “lucky” after a cut was found post-race.
The company has nonetheless already ruled out high wear as a cause of the incidents.
Lance Stroll suffered a left-rear failure as he approached the pit straight after spending the opening 30 laps on the Hard tyres on which he started.
Race leader Max Verstappen then encountered a failure on a left-rear Hard tyre along the start/finish straight during the closing stages.
Pirelli is set to fly the damaged tyres, as well as other sets, to its laboratory in Milan on Monday in order to begin a thorough investigation.
“Looking at the tyres used in the second stint, for most of the drivers we didn’t find any evidence, or anything [of damage],” said Pirelli chief Mario Isola.
“I believe I can exclude that failures were due to tyre wear, because it is not a matter of tyre wear.”
Isola pointed out that other drivers, notably Ferrari’s Charles Leclerc and McLaren’s Lando Norris, had carried out longer stints on the Hard tyres compared to Stroll and Verstappen, thus ruling out excessive wear as a factor.
He added that “the preliminary investigation is that it is probably due to an external factor or debris, [a] kerb, or whatever, but I don’t want to jump to a [full] conclusion.”
He emphasised that the right-rear tyre, rather than the left-rear, is the one that is most stressed around the six-kilometre Baku City Circuit.
Isola also revealed that Pirelli “found a cut on the inside shoulder of the rear-left tyre used by Hamilton in the same stint, the cut was quite deep and big, and probably 6-7 cm.
“But [it was] not cutting the construction, so the tyre was still in one piece, just the tread is cut, and when there was the red flag and Lewis came to the pit lane and changed the tyres we were able to find the cut.”
Isola showed attending media a picture of Hamilton’s cut tyre and confirmed that it had “clearly come from debris, it is clear, because the tyre is clearly in one piece, and the cut is not in any direction…. it is clearly from the outside.”
Isola added that “in the case of Lewis, the cut was not deep enough to cut the construction, so he was lucky because of that, and in the case of Max and Lance there was an air loss and therefore a failure.”
Isola affirmed that Pirelli hopes to present a full conclusion prior to the next event in France.