Pirelli has ruled out a structural failure of its tyre as the cause of Sebastian Vettel's puncture during the Abu Dhabi F1 GP.The Italian tyremaker, Formula 1's sole tyre provider for now, suggested in a statement that debris on the track could have caused the World champion's first race retirement in more than a year."Having subjected the tyre to minute analysis," Pirelli said, "structural failure of the tyre or valve has been ruled out as a cause of the incident. Track debris or other outside circumstances cannot be excluded as a possible cause." Motorsport director Paul Hembery added, however, that a close inspection of the track had provided no direct evidence to support the debris theory.RECORD EARNED, MISSEDPirelli said the right rear tyre was part of a set of softs that the Red Bull driver had used on the day before to take a record-equalling 14th pole position of the season.The tyre was shredded as Vettel nursed his car back to the pits after the puncture in the opening seconds of the first lap. The structural damage caused by the flailing rubber, and the car running on a rim forced Vettel to retire in the pits.The race was won by McLaren's Lewis Hamilton; the puncture ended Vettel's hopes of equalling Michael Schumacher's record of 13 wins in a season.