Michelin logistics and qualifying tyres

LOGISTICS, TYRE RANGE, AND QUALIFYING TYRES No fewer than 55 cars turned up for the obligatory scrutineering and test day prior to this year's Le Mans 24 Hours, with every team working hard on last-minute preparations. As ...


No fewer than 55 cars turned up for the obligatory scrutineering and test day prior to this year's Le Mans 24 Hours, with every team working hard on last-minute preparations. As for Michelin, the key task centred on fitting tyres for the 39 cars that will run on the French rubber. We take a closer look at the logistics behind the operation, the range of tyres available, and focus on the tyres that will be used for qualifying.

*Michelin logistics for the Le Mans 24 Hours: a well-rehearsed ballet !
8000 tyres
20 semi-trailers
28 technicians
55 fitters and stock controllers,
15 chemists, researchers and technical assistants.

The Le Mans 24 Hours is a priority fixture for Michelin. This year again, a fleet of 20 semi-trailers will haul some 8,000 tyres to the French circuit.

"You need around thirty sets of slicks per car, plus intermediate and rain tyres," says Gerard Bombled, Michelin Competition's Endurance Programme Operations Manager.

Amongst the 55 fitters, there are 10 people who usually work on the World Rally Championship, as well as 18 Italian fitters and 12 students from the Henri Laurens Technical College in Saint Vallier, France.

The fitters work in four different tents, one for each category. The 8,000 tyres are carefully stored in the vast new 800 sq. metre marquee which Michelin will inaugurate at this year's race, doing away for the need to work out of the backs of semi-trailers as has traditionally been the case.

* The Le Mans Michelin range

Dry weather tyres... four compounds

For Le Mans, we have three main types of compound ('soft', 'medium' and 'hard'), plus a special compound for higher temperatures that is generally used for the first stint of the race. We plan around thirty sets of slicks per car for all four categories, which means we will have twenty or so different types of slick at Le Mans." The ideal working temperature for a slick is between 80 and 100C.

Intermediates... two compounds

In conventional circuit racing, drivers tend to run on either dry weather tyres or full wets. In the case of Le Mans, intermediates are more frequently used because of the circuit's length and also because its surface is not all that abrasive. Michelin's range of intermediate tyres features a choice of two compounds. Matthieu Bonardel: "It is extremely difficult to develop intermediate tyres because the characteristics of the test track you use has such a big influence. For Le Mans, intermediates can also be asked to last one or even two stints because the track can stay wet for some time after rain has fallen."

Rain tyres... one compound

Here again, the evolution of rain tyres is complicated by the fact that they account for a mere 5% of the total number of tyres used during a full season. Even so, Michelin makes a special point of pursuing their development. Matthieu Bonardel: "Since 2004, we have profited from the Le Mans Series and the different races which have taken place in the wet to develop our rain tyres. We frequently encounter very wet conditions during the different rounds of the LMS and we have won the LMS every year since 2004, so our products are clearly competitive." In damp conditions, rain tyres wear little because they are 'lubricated' by the water and can cover up to five or even six stints. But when the track begins to dry out, the rate of wear increases very quickly. The optimal working temperature of a rain tyre is between 40 and 50C, while the minimum sea-to-land ratio (proportion of grooves) is 25%.

* Marked qualifying tyres ...

For the first time at the Le Mans 24 Hours, Michelin will mark the sides of their tyres so that the public and the media will be able to spot at a glance the 39 cars running on the French rubber. This new system will be used in qualifying (from 13-14 June) and it will be tested for the first time today.

Two types of qualifying tyre will be available: a super-soft compound, that will be quick only for one lap and so is best-suited to experienced drivers and a normal soft tyre, which will last for another lap.

"Getting the most out of a set of qualifying tyres is an art," explains Matthieu Bonardel. "The drivers are amazed by their performance for they allow them to brake 30 metres later and to corner 20kph quicker. They can feel the tyres climb progressively to their full potential. Then, for a short period, grip is phenomenal before performance suddenly falls off, almost as though they had suffered a puncture, or driven over a patch of oil."

-credit: michelin

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Series Le Mans