<p>Pirelli’s Formula One tyres came under renewed scrutiny on Friday after triple world champion Sebastian Vettel suffered a blowout in second practice at the Belgian Grand Prix. <br /><br /></p>.<p>The Red Bull driver was fastest in the session but the sight of him nursing his stricken car back to the pits at slow speed with strips of right rear tyre buckling and flailing was more of a talking point. <br /><br />Pirelli, who had to strengthen their tyres after a spate of blowouts at the British Grand Prix in June threw the sport into crisis, said Vettel had suffered a puncture and they were investigating what caused it. <br /><br />Last month’s Hungarian Grand Prix, the last race before the summer break, was free of tyre-related incidents but the Hungaroring is one of the slowest circuits while Spa is the second fastest track with heavy loads on the tyres. Vettel had earlier lapped with a best time of one minute 49.331 seconds with the sun coming out after a damp start to the day in the Ardennes forests where the weather is notoriously capricious. <br /><br />The championship leader’s time looked ominous, 0.059 quicker than second placed team-mate Mark Webber and comfortably clear of Frenchman Romain Grosjean in the Lotus with a time of 1:50.149. <br /><br />Ferrari's Fernando Alonso set the largely unrepresentative pace in the opening session with a lap of 1:55.198 as Formula One drivers shrugged off the long August break and got back up to speed.</p>
<p>Pirelli’s Formula One tyres came under renewed scrutiny on Friday after triple world champion Sebastian Vettel suffered a blowout in second practice at the Belgian Grand Prix. <br /><br /></p>.<p>The Red Bull driver was fastest in the session but the sight of him nursing his stricken car back to the pits at slow speed with strips of right rear tyre buckling and flailing was more of a talking point. <br /><br />Pirelli, who had to strengthen their tyres after a spate of blowouts at the British Grand Prix in June threw the sport into crisis, said Vettel had suffered a puncture and they were investigating what caused it. <br /><br />Last month’s Hungarian Grand Prix, the last race before the summer break, was free of tyre-related incidents but the Hungaroring is one of the slowest circuits while Spa is the second fastest track with heavy loads on the tyres. Vettel had earlier lapped with a best time of one minute 49.331 seconds with the sun coming out after a damp start to the day in the Ardennes forests where the weather is notoriously capricious. <br /><br />The championship leader’s time looked ominous, 0.059 quicker than second placed team-mate Mark Webber and comfortably clear of Frenchman Romain Grosjean in the Lotus with a time of 1:50.149. <br /><br />Ferrari's Fernando Alonso set the largely unrepresentative pace in the opening session with a lap of 1:55.198 as Formula One drivers shrugged off the long August break and got back up to speed.</p>