Formula One's tyre crisis deepened today when world governing body, the FIA, spelled out the options facing Michelin teams in the United States Grand Prix at Indianapolis.
Michelin have conducted urgent tests on their tyres after Ralf Schumacher's failure on Friday but have still not discovered the reason for his puncture.
They have today advised their teams - McLaren, Williams, BAR, Toyota, Sauber, Red Bull and Renault - not to race on their current tyres.
Instead they put forward suggestions to use an alternative tyre, which is against Formula One rules, or add a chicane to the banked final turn, which is the cause of this weekend's problems.
Michelin's request for a chicane has been comprehensively ruled out by the FIA's race director Charlie Whiting in a letter to the teams.
It read: "To change the course in order to help some of the teams with a performance problem caused by their failure to bring suitable equipment to the race would be a breach of the rules and grossly unfair to those teams which have come to Indianapolis with the correct tyres.
That has left Michelin teams with three options: run different tyres and risk a severe penalty, make repeated pit stops to change the troublesome tyres or deliberately drive slower through the final turn.
