Red Bull admit they are unlikely to find out what caused Sebastian Vettel's tyre failure at the Abu Dhabi Grand Prix.
Vettel crashed out on the first lap at the Yas Marina Circuit after suffering a puncture and Pirelli and Red Bull launched an investigation after the race. However, the Italian manufacturer on Wednesday ruled out structural failure as a reason and also doubts debris was to blame.
Red Bull team boss Christian Horner insists they didn't pick up any problems with the tyre before the race got underway and concedes they are unlikely to come up with answers in the future.
"We have worked hard with the full assistance of Pirelli to find an answer, but unfortunately when you are presented with a bag of bits it is almost impossible to come up with a firm answer," Horner told Autosport.
"There is nothing on the data to suggest there was anything wrong with the tyre before the start, but when he ran across the kerb on the exit of Turn 1 there was an instant deflation. We believe the most likely cause of this was a foreign object penetrating the tyre, but we may never find the true answer."
On-board footage from Jenson Button's car on the grid showed smoke coming from Vettel's right rear tyre on the star, but Horner explained that it was burning bodywork.
"There was some worn bodywork that got burned, and that gave the appearance of smoke from the tyre after the start," he said.
"Sebastian's start procedure was the same as Mark's, and the same it had been all season. We were also running in the same configuration as before, so there is no reason why we should suddenly suffer a problem."
Pirelli rules out structural failure