Bridgestone investigating MotoGP riders' Assen tyre problems

Yamaha's Ben Spies and Ducati riders Valentino Rossi and Hector Barbera all suffered from problems with their rear Bridgestone in the closing stages of the Assen event. Spies and Barbera managed to keep going for fourth and seventh respectively, while Rossi pitted for a replacement and finished 13th.

Spies said he had been concerned that the tyre might fail completely, particularly as he was in the middle of a tough fight with Andrea Dovizioso.

"A chunk came out of the tyre and then a second; I couldn't do anything about it," he said. "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."

Barbera had to back off in his dice with Nicky Hayden and Cal Crutchlow as the problem worsened.

"With five laps to go, I tried to overtake Cal, but I lost the rear grip and from that moment I started to have an issue with the back tyre, losing both my race pace and my confidence," said the Pramac rider. "I gritted my teeth until the flag to achieve seventh place."

Shinichi Yamashita, head of Bridgestone motorsport's development department, said an investigation would begin immediately.

"Unfortunately a few riders experienced a problem with their rear tyre today and we sincerely apologise to those riders affected," he said.

"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."