A Proud Record
Ten wins in a row : Michelin boasts an outstanding record at Le Mans with no fewer than 16 victories on the famous circuit in the Sarthe. And we shouldn't forget that Bibendum was in on the very first running of the race that was to become the stuff of legend : in 1923 Michelin supported Lagache and Leonard in their Chenard and Walker Sport entry.
Some 55 years later Michelin was back in business at Le Mans, sharing the success of Renault Sport and the Alpine A442B driven by Jean Pierre Jaussaud and Didier Pironi in 1978. Today, endurance racing for Michelin is still the same extraordinary forcing-ground for research and development that it was back then.
"What fascinates us about endurance racing, "says Michelin Group competitions director Frederic Henry-Biabaud, "is that it presents us with not one but three challenges. First, pure performance, i.e. outright speed; then consistency, with tyres needing to stand up to severe punishment over a long period of time, and lastly sheer endurance -- three basic attributes that have to go together."
Michelin has always numbered major constructors among its partners. In 1989 Michelin's link-up with Sauber-Mercedes proved a winning , as did those with Peugeot in 1992-93 and McLaren in 1995. In 1998 Bibendum and Porsche threw in their lot together on the Sarthe circuit and were first across the line. In 1999 it was BMW's turn to join Michelin on the top step of the podium, then Audi and Michelin embarked on a successful streak in 2000 that carried right through to 2007. The only break in the German manufacturer's winning run came when Bentley won in 2003 - but the English prototype also wore Bibendum boots.
With 10 straight wins behind it, Michelin is back with one aim in mind : winning again and extending that extraordinary sequence. "Le Mans is our stamping-ground," adds Frederic Henry-Biabaud. "There's no question of not winning at Le Mans. It's a compelling event, in philosophical terms as well. For me, Le Mans is not the same as other sporting conflicts. It's a hugely popular event, of course, but Le Mans is also about that fundamental rapport with the constructors."
Roll on victory number 11!
TYRE PRESSURES
Endurance racing, and more particularly the Le Mans 24 Hours, is the only form of motor racing where the drivers set off for more than two and a half hours at a time without getting a chance to adjust their tyres. Michelin's technical staff must consequently be able to anticipate changes in the weather conditions in order to optimise pressures before tyres go on the car.
In Formula 1 and MotoGP, tyre pressures are carefully adjusted before the start, while in rallying the drivers will systematically check their pressures themselves before each stage. At Le Mans, however, the drivers can cover two, three or even more stints at a time - which can mean more than two hours on the track - without doing anything to their tyres, despite the inevitable increase in air pressure as heat builds up inside them. Getting tyre pressures right optimises their efficiency. If the pressure is too high, or too low, performance will suffer. In endurance racing, the art consists in anticipating the ideal pressure as a function of how the temperature is expected to change and only Michelin's technicians are qualified to do this.
The temperature factor
"Tyres are always inflated cold," explains Bernard Jay, endurance tyre developer at Michelin in charge of prototypes, "but we take into account the time at which the tyres will be out on the track and how ground temperatures are likely to evolve. For example, at Le Mans, the tyres that go on for the start are not inflated to the same pressure as those which will be fitted after the first driver/tyre change which is generally early in the evening, and so on. The exact pressures are based on Michelin's years of experience of the French race as well as on work done in testing with our partner teams. We keep records going many years back of all the temperature graphs recorded at Le Mans." After being inflated, the tyres are stocked on special heating racks until their time comes to go on the car. "Just in case the unexpected arises, such as a sudden shift in the weather, we tend to have a full set of intermediate or rain tyres ready that we don't put on the heating racks, just in case--"
Dry air
Michelin tyres are inflated using dry air. With the exception of certain American events where nitrogen is employed - and even then more by force of habit - tyres are inflated with dried air to prevent moisture from influencing the build up of pressure.