On Saturday 17 June, Audi will become the first major manufacturer to launch an assault on the Le Mans 24 Hours with a diesel powered car – and Michelin will play an important role in trying to help the R10 follow in the footsteps of the ultra successful R8.
The decision to switch to diesel power with the R10 is not only a bold gamble for Audi, it has also been a significant challenge for Michelin whose tyres have taken the German carmaker to victory at Le Mans on five occasions since 2000.
The extra torque of the diesel powered R10 has been the topic of much conversation heading into the most famous endurance race of them all, although the true challenge for tyres this coming weekend at La Sarthe will continue to be dealing with the constraints of running at forces equal to those experienced in
Formula One for the equivalent of three Grands Prix…
"Engine torque? That, we can handle," Michelin Competition's circuit racing programme
manager Matthieu Bonardel said regarding the torque situation with the R10. "If only that was the only problem we faced…"
The technical characteristics of the Audi R10 have understandably had a knock-on effect concerning tyres on several fronts.
For a start, the block of the R10 is heavier than that of the V8, and the weight split is also different - meaning there is more weight on the rear tyres. The endurance factor then comes into play, since it is safe to presume that the drivers will put in longer stints, which means the tyres will cover longer distances. And with a maximum power of 650hp, the TDi engine is also something like 15 per cent more powerful than the former FSi block, so this too will make bigger demands on the tyres. Finally, there's the torque…
"But torque is not a problem if the vertical load is applied correctly onto the tyres, that is to say if the aerodynamics are well honed and if the traction control system is optimised,” Bonardel insists. “High torque is a challenge for the drive train, but not necessarily for the tyres."
Ironically, to combat wheelspin of the rear wheels, Michelin's developers have worked on the front tyres.
"Torque is effectively ten times higher under high speed braking because of aerodynamic downforce,” Bonardel continues. “However, the phenomenon of weight transfer means it's the front tyres that suffer the most. At the same time, the prototypes have a tendency to understeer. So, to optimise the balance of the car and to provide additional grip, we have increased the diameter of the front tyres by 30mm."
Three centimetres doesn’t sound like much – but it will change a great deal.
The men from Michelin have been working on the Audi R10 project for three years now, with this years race the moment when both parties hope the work carried out will yield results.
