MotoGP tyre supplier Bridgestone have launched an investigation to find out the reasons why Valentino Rossi and Ben Spies' tyres fell to bits in such a dramatic fashion in yesterday's Assen round.

The Doctor was forced to pit in and change tyres after big chunk fell out of his rear while Ben Spies soldiered on with his tyre but lost a potential podium spot to Andrea Dovizioso. "A chunk came out of the tyre and then a second; I couldn’t do anything about it. I was hoping Dovi would get past me as I was worried the tyre would explode and I didn’t want to fall right in front of him," said the Texan.

The chunks all came out of the right shoulder of the assymetic harder rear. It also happened to Pramac Ducati's Hector Barbera. All this happened just one meeting after Casey Stoner slammed the firm because the performance is his tyre at Silverstone disappeared after five laps.

“Unfortunately a few riders experienced a problem with their rear tyre today and we sincerely apologise to those riders affected. We have commenced a full investigation into the matter and I will personally take the affected tyres back to Bridgestone’s Technical Centre in Japan tomorrow where they will undergo detailed analysis to determine the cause of this issue," said Bridgestone's Shinichi Yamashita.