By Luc Fradette

Jean-Philippe Weber, Michelin's director of motorcycle racing said he does not understand Valentino Rossi's decision to switch from Michelin to Bridgestone tires next season.

Rossi declared himself unhappy with the overall performance of the Michelin tires in 2007. Rossi endured a difficult season with Yamaha, and was unable to match the blazing pace set by new champ Casey Stoner who was riding a Bridgestone-shod Ducati.

"In my opinion things changed at the end of the season, as far as we are concerned, but Valentino felt that the problem was just the tire, not something else," said Weber. "Maybe this is a good analysis, or maybe it isn't. For me, there were problems on the bike as well as with the tires."

Rossi and his new teammate at Yamaha, Jorge Lorenzo, will use different tires in 2008.