Yamaha ask for specific tyres

Rossi is now 44 points adrift of championship leader Casey Stoner, and the Italian has said that he feels tyres have been too important this season.

Yamaha have also said that Bridgestone's advantage over Michelin is making the difference, and they are hoping to work closely with the French tyre manufacturer to improve their performances.

"We've asked Michelin to make a bigger effort in producing a tyre specifically for our bike," Yamaha's general manager for engineering operations, Masao Furusawa, was quoted as saying by Italian magazine Motosprint.

"We've put all our data at Michelin's disposal. The influence of the tyre is incredible now, and Bridgestone is better than Michelin, absolutely."

Furusawa admitted that Yamaha could switch to running Bridgestone tyres, especially as the majority of their road bikes use the Japanese rubber.

However, he also admitted that he was unsure if Bridgestone would want to up its workload, and he said that he is currently focused on making improvements with Michelin.

"The Michelin is a more specific tyre," he said. "It must improve in traction and in the phase when the bike leans a lot in the curves. And it obviously must guarantee a greater consistency in its performance."

Michelin has taken four wins so far this season, while Bridgestone has won seven times.