Findings of Pirelli’s Vettel tyre investigation revealed

Pirelli’s investigation into Sebastian Vettel’s late-race tyre failure in Belgium has suggested that a cut from track debris was the most likely cause, with the Ferrari driver’s one-stop strategy making his worn rubber more prone to such damage.

Formula One racing’s governing body, the FIA, confirmed on Thursday that it was satisfied with the thoroughness of Pirelli’s exploration of Vettel’s incident, and that of Mercedes’ Nico Rosberg, who also experienced a high-speed tyre failure in Friday practice at Spa-Francorchamps.

Tests were carried out on tyres used by different teams during the race and none showed any signs of internal delamination (fatigue). However, Pirelli engineers reported a highly unusual number of cuts to tyres over the Spa weekend, one of which caused Rosberg’s failure. This led to the FIA agreeing to Pirelli’s request to have the track cleaned after qualifying.

Of Vettel’s incident, which removed the German from podium contention with less than two laps to go, Pirelli reported that the remaining tread thickness on his rear tyres was approximately 30 percent at the time of the failure, making them more susceptible to damage from even small debris.

After the race, Vettel defended Ferrari’s one-stop strategy - his key rivals all made two or three stops - insisting that it had been a joint decision between himself and the team, and that it “was never risky, at any point.”

Pirelli have previously suggested that rules and not teams should determine maximum stint lengths during races and the FIA has said it is willing to consider any safety recommendations made by Pirelli for this weekend’s round in Italy and for the remainder of the season. Pirelli have already proposed a study to evaluate ways in which circuits can be cleaned most effectively.