Michelin will quit Formula One at the end of next year because of the governing body's decision to move to a single tyre supplier from 2008, the French manufacturer said on Wednesday.
The decision leaves Japan's Bridgestone on their own in 2007, as they were after Goodyear ended their 33-year involvement in 1998 and before Michelin returned to reignite the 'Tyre War' in 2001.
"This decision is the result of the realisation there is a profound disagreement between the sports philosophy that has always been driving Michelin and the management practices of the F1 authorities," company boss Edouard Michelin said in a statement.
The company said the uncertainty thrown up by the International Automobile Federation (FIA), with "constant changes to racing regulations without warning", made planning for the future impossible and did not give sufficient guarantees to justify long-term investment.
Michelin supplied seven of the 10 Formula One teams this year and will have six next year. Williams and Toyota have joined Bridgestone while Red Bull-owned Scuderia Toro Rosso, formerly Minardi, have switched to Michelin.
The French tyre maker, the world's biggest, clashed with the FIA over the US Grand Prix fiasco in June when their teams failed to start due to tyre safety concerns at Indianapolis.
The French group said partner teams had convinced them the move to one tyre supplier is now "inevitable" and the decision to quit had been made in accordance with the required notice period.
"Michelin's withdrawal at the end of 2006 will almost certainly bring into play a single tyre supplier in 2007," said the statement.
"It should be possible to verify if the FIA's vaunted advantages of [having a single supplier] are proven and, in particular, if equality amongst teams really is guaranteed."
The FIA expressed gratitude to Michelin for their contribution but pointed out the teams had "repeatedly and unanimously" requested a single tyre supplier.
The governing body said teams would be glad to have their wish granted earlier than expected.
"A single tyre supplier will undoubtedly make Formula One fairer, safer and less expensive for the teams but, above all, it will avoid a repetition of the problem which arose at the 2005 US Grand Prix," it added.