Vettel says tyre failure is a 'question mark'

The Ferrari driver retired from the lead of the race when his tyre exploded at the start of lap 26 of 71, as he tried to stretch his first stint as far as possible.

Vettel said there were no warning signs in the car that his tyres were in trouble, and he went to the Ferrari pitwall when he returned to the paddock to see if the team had any further idea.

"The tyre exploded out of the blue," he said. "No signs before that, everything was normal.

"Everything was the same as the lap before, no signs of the failure.

"It's completely a question mark on why the tyre failed."

Vettel does not believe Ferrari was pushing the boundaries by trying to stretch its tyre life.

"It was clear everybody had much more tyre life than expected, so 27 laps is not much on that [super-soft] compound," he said.

"Everybody was trying to go longer on the tyres.

"Kimi [Raikkonen] did more than 20 laps on the ultra-soft, there were other people who did more laps on the super-soft.

"So out of nothing the tyre exploded."

Pirelli explained to Autosport it is trying to analyse the failure, although it has very little to work with given the whole tread was lost in the incident.

It also said initial claims the failure was caused by debris were wide of the mark, as there is no proof yet of the cause.

However, analysis of the super-soft tyres Raikkonen used in his opening stint - pitting on lap 22 - showed high wear, which can make the rubber more susceptible to debris or damage suffered by running over kerbs.

Ferrari team boss Maurizio Arrivabene said part of its investigation would look into the fact that Vettel was the only driver to suffer a failure.

"We are talking with Pirelli to understand the reason," he said.

"Other teams were running without any problem. This is really strange.

"Seb, without his tyre failure, he was [going to finish] very high on the podium.

"I don't know where, but very high."