mollyfamwatPirelli has told the FIA that it believes debris from brake discs was responsible for problems during FP2 and FP3 in Baku. Pirelli motorsport director Paul Hembery said: “We have a feeling that the braking material may have been the reason for the problems.” However, the FIA is not able to rule out other factors to which Pirelli is not privy. Hembery says the investigation will continue and that the company is confident that the problems experienced in Baku were caused by debris.
On Saturday night, Pirelli issued a statement that suggested a possible cause for the tyre failures during the European Grand Prix at Baku. It said: “Pirelli’s analysis of the Baku circuit has revealed unusual concentrations of aggregates (solid particles) in specific locations, resulting in a specific phenomenon on the circuit. “Pirelli has been investigating this phenomenon with its supplier and the FIA since Friday evening”.
Pirelli suspects that two punctures at Sunday’s Azerbaijan Grand Prix were caused by debris, but will not draw any definitive conclusions until a full investigation has been carried out at the Milan base this week. 
1 Connected Lance Stroll and Max Verstappen were shocked after two separate 160mph crashes caused by a faulty left rear tyre in their cars. Due to Verstappen’s accident, the race was halted with two laps to go, resulting in a sprint race won by Sergio Perez. The similarities between the two accidents have raised questions about the causes of the breakdowns, but a gash found in the left rear tire of Lewis Hamilton’s car could provide the answer. The cut in Hamilton’s tyres was not deep enough to cause a stoppage, but debris somewhere on the track is believed to have damaged the tyres of Stroll and Verstappen’s cars. Pirelli also ruled out a tyre failure due to excessive wear, as none of the tyres fitted to the vehicles had an abnormally low tread depth at the time of the failure. I think I can rule out that the defects were due to tyre wear, because it is not a question of tyre wear, said Pirelli motorsport director Mario Isola. We found a cut on the inside shoulder of the left rear tire that Hamilton used in this section. Max Verstappen has withdrawn from the Azerbaijan Grand Prix after a puncture Evgeny Safronov/Getty Images The cut was quite deep and wide – probably 6-7 cm – but did not cut into the structure, leaving the band intact. There was a cut in the tread [on Hamilton’s tyres] and when the red flag went and Lewis went into pit lane to change tyres, we were able to find the cut. In Baku, the left rear is not the most loaded, because when you talk about the tires, the right rear is clearly the most loaded. This is a preliminary investigation. Isola said the subsidence theory is supported by the nature of the failures, which occurred suddenly and without warning from the vehicles’ tire pressure sensors. The teams added that there were no signs or warnings. We need to get the telemetry from them, but they said there was no warning, no vibration, nothing to indicate a problem with the tires. Remember, the tires that were on the wreckage came back to the garage and our staging area a few minutes ago, we need time to analyze them – I don’t want to draw any premature conclusions. But it looks like a cut in the rubble. It’s not a tire with more pressure and we have evidence of another cut in the same place [on Hamilton’s tire]. Both accidents happened in about the same part of the track with a few laps difference, so we have other cars with the same number of laps, with the same tires, with no problem. So from the preliminary investigation it seems that it’s probably an external factor or a piece of debris or an indentation or something else, but I don’t want to jump to any conclusions, because the plan now is to do a thorough investigation and prepare a report for the teams and the FIA, which hopefully will be ready for Paul Ricard. This is clearly a priority.
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