Tyre manufacturer Goodyear yesterday gave the thumbs-down to F1's new grooved tyre regulations by announcing it will withdraw from grand prix racing at the end of the 1998 season.

The decision will rock F1 to its core, bringing to an end lucrative tyre supply contracts worth in excess of £8 million a year for top teams such as Ferrari, Williams, McLaren and Benetton.

It also means that Bridgestone, the Japanese tyre maker which entered F1 this season, will under the current rules have to provide tyres for the entire grand prix grid unless another company decides to take Goodyear's place.

"Rules imposed for race tyres in 1998, the ever-escalating cost of participation and the consequent diminishing return on the company's investment are the major factors in the decision," said William J Sharp, president of the company's global support operations.

"The rule changes imposed by the F1 governing body to tyres with grooved treads sets a direction in our development programme of complying with costly new specifications rather than with the objective to advance technology."

Cars fitted with Goodyear tyres have won a record 361 grands prix since the company made its F1 debut on the works Brabham cars in 1964. Despite Bridgestone's presence this year, the most recent non-Goodyear victory was in the 1991 Canadian grand prix when Nelson Piquet's Benetton won on Pirelli tyres.

It is ironic that Goodyear's withdrawal may have the same effect as the FIA's decision to introduce grooved tyres, namely a reduction in lap speeds. If Bridgestone is the sole supplier in 1999, the inevitable trend will be towards more durable, harder tyre compounds which will reduce lap times. Yet if the French company Michelin should return to F1 after an absence of 14 years, the lap-speed spiral could continue unabated.