Sauber switches to Michelin.

The Sauber Petronas team has surprised the Formula One paddock by signing a contract to switch to French tyre manufacturer Michelin with immediate effect.

Despite having been rumoured in the past, the announcement is something of a shock as Sauber had been expected to remain with Bridgestone after the Japanese company enjoyed greater success than its rival in 2004. Keeping the status quo would also have kept the Swiss team aligned with engine supplier Ferrari, which took 15 wins on Bridgestone rubber this season, but it is understood that Sauber was becoming increasingly frustrated at seeing the champions getting a bigger say in how the tyres were developed.

"I'm very pleased that we were able to sign this contract with Michelin, and I'm looking forward to a successful co-operation," team boss Peter Sauber said, "At the same time, however, I would like to thank Bridgestone for a good partnership during the past six years."

Sauber will conduct its first test on Michelin tyres later this month, running in Barcelona between 24-26 November.

"As we demonstrated in 2004, our technology makes a significant contribution to the performance of Formula One cars equipped by Michelin," the tyre company's head of competition operations, Pierre Dupasquier, commented, "I look forward to enabling Sauber to benefit from this progress."

The switch will see Sauber's new arrival, Jacques Villeneuve, remain on Michelin rubber after three races with the Renault team, but Felipe Massa, who will partner the Canadian in 2005 following the departure of Giancarlo Fisichella, will get his first taste of the French tyres during this month's test.

Sauber's move tips the 'balance of power' among the tyre manufacturers heavily in Michelin's favour - too heavily in fact. Each company has to display the capacity to supply four of the ten teams, and its is expected that at least one rival operation will make the move in the operation. Toyota is the current hot tip to switch to Bridgestone although, with the future of Jaguar, Jordan and Minardi still undecided, it remains to be seen exactly what moves might be made.