The F1 title challenges of dominant Michelin-shod teams McLaren and Williams could be dealt a body blow if the FIA changes the way it measures tyre widths for the upcoming Italian Grand Prix.

The F1 title challenges of dominant Michelin-shod teams McLaren and Williams could be dealt a body blow if the FIA changes the way it measures tyre widths for the upcoming Italian Grand Prix.


The French tyre supplier may be forced to scrap its current specification tyres before the next round of the F1 world championship at Monza on September 14.


F1's governing body wrote a letter to all the teams this week claiming the previous tread width limit of 270 mm for the front tyres will now be measured after the race - rather than before it, as had been the previous practice.


According to , the new ruling will hurt Michelin more than Bridgestone because its tyres have used the 270 mm limit to the maximum. It's believed McLaren-Mercedes and Williams-BMW have been able to make inroads into Ferrari's lead in the championship because Michelin has a clear performance advantage over Bridgestone at this stage of the season.


Confirming the FIA's decision, Williams' chief operations engineer Sam Michael said: "The FIA have changed the way they measure the front tyre contact patch. They will now be measuring the contact patch new as well as worn. We are reviewing the consequences of that."


The new ruling is believed to have come after complaints from Michelin's rivals Bridgestone - who claim that when the French tyre manufacturers' rubber wears down during a race the tread width of the tyre exceeds the 270 mm limit. There may also be instances that the tread width exceeds the limit when the tyre is running at speed, although this is difficult to prove.


Although Michelin is expected to fight the decision, because it claims the tyre design has been fully legal since it was first used at the 2001 San Marino Grand Prix, it could be forced to build completely new designs for Monza.


There may not be enough time for Michelin to prepare these tyres in time for the pre-Monza test this week - which means Williams and McLaren could race with tyres at the Italian event which have not been tested before.

Original article from Car