Sudden tyre failure wrecked Lewis Hamilton's hopes of a home British Grand Prix victory on Sunday after the Mercedes driver had led from pole position.
Formula One's 2008 world champion led from the start but suffered a dramatic failure on lap eight when his left rear tyre suddenly deflated on the Wellington Straight at Silverstone.
The Briton struggled back to the pits on three wheels and a rim, with the remains of the tire carcass flailing around, before he could pit in 18th place and resume in 21st.
Ferrari's Brazilian Felipe Massa suffered a similar failure two laps later, pitting and returning in last place, before Toro Rosso's Jean-Eric Vergne brought out the safety car with another blowout on lap 15.
With three rear left failures in quick succession, drivers were advised to take care over the curbs with teams trying to work out whether the problem lay with the Pirelli tires or debris on the circuit causing punctures.
Red Bull's Sebastian Vettel led the race but the team said they had also found cuts in the German's left rear tyre at the pitstop.
McLaren's Mexican Sergio Perez also had a rear left tyre failure in Saturday practice.
"There is a lot of debris out there but I'm working in the dark at the moment. We've not heard anything from Pirelli," McLaren chief executive Jonathan Neale told the BBC during the safety car period.
"The drivers have done amazingly well under the circumstances. We have to make sure our drivers are safe."
Pirelli's motorsport director Paul Hembery said at the time that first findings indicated Perez's failure was caused by a cut in the inner sidewall.
"Something went into the tyre, pierced it, and then came out again, in the direction of travel. Whether that was a piece of debris or the edge of a curb is hard to say," he said on Saturday.
The Pirelli boss said the Perez failure was unrelated to delamination problems suffered in previous races where the tread peeled away from the body of the tyre, which remained inflated.
Pirelli changed their production process after the previous race in Canada.
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