At the stroke of 4 p.m. on the afternoon of Saturday June 12th, the 2004 Le Mans 24 Hours will get under way in the form of a rolling start. Exactly half the field - twenty-four cars out of forty-eight - will be running on Michelin tyres which...
At the stroke of 4 p.m. on the afternoon of Saturday June 12th, the 2004 Le Mans 24 Hours will get under way in the form of a rolling start. Exactly half the field - twenty-four cars out of forty-eight - will be running on Michelin tyres which will not only be out to secure a seventh consecutive outright win in La Sarthe, but also success in every category, just as they did this time last year.
The challenge they face is one of the toughest in motor sport, including top speeds of up to 325 kph and average speeds of more than 210 kph, sometimes for as many as four stints. That's close to 700 km, with only three lightning refuelling stops to break up the unrelenting pace of the French classic.
As ever, in tyre terms, the keys to success will be performance, endurance and consistency, but the ability to anticipate, react and adapt is equally essential, especially if the weather proves fickle. In which case, the unique experience and savoir-faire of Michelin's technical staff once again promises to be a valuable asset to the French tyre firm's partner teams.
The essential facts at a glance...
The special fascination of the Le Mans 24 Hours lays in a myriad of details which demand scrupulously careful attention, whether you're a driver, team or tyre manufacturer.
Michelin Competition's Frederic Henry Biabaud (Deputy Director), Matthieu Bonardel (Circuit Racing Programme Manager) and Gerard Aussage (Endurance Programme Manager) describe the key points behind the unique challenge of this legendary race.
Durability - or rather 'durable performance' to be precise - is one of the keys to Michelin's enviable record at Le Mans where its tyres which have gone unbeaten since 1998.
The regulations place a limit on the number of mechanics authorised to work on cars in the pit-lane at any one time, and even on the number of nut-guns that can be used, so tyre changes are clearly costly in terms of time. The objective is therefore to cover as many stints as possible with the same set of tyres - without compromising either safety or performance - and to make tyre changes coincide with driver swaps, another time-consuming operation.
"Drivers don't want to begin their stint on tyres that have already covered one or two stints in the hands of a team-mate," points out Gerard Aussage. "They prefer to start their run with fresh rubber so they can manage their tyres as they see fit."
A feature of Michelin's Le Mans tyres is their ability to cover two or three stints of twelve or thirteen laps each. During last year's race, Bentley and Michelin accomplished the exploit of covering four stints in daylight, with track temperature around 25C. It was a first not only for the British team but also for Michelin
"We had already succeeded in doing quadruple stints, but only during the night when temperatures were cooler," explains Gerard Aussage. "During the day, we are in fact closer to the drivers' own physical limits." It is important to realise that four stints at Le Mans represent close to 700 km, that is to say over three hours at the wheel at an average speed of more than 210 kph! In the middle of June, inside a closed cockpit, that's a genuine test of driver stamina. And often it's the driver who 'cracks' well before the tyres reach their limit...
Quintuple stints for the first time in 2004?
A new regulation introduced for this year's Le Mans 24 Hours could well change the picture for Michelin: the reduction in fuel tank capacity from 90 to 80 litres.
Matthieu Bonardel: "Less fuel means shorter stints, probably one or two less laps per stint. It is therefore possible teams will ask us to cover four stints with the same set of tyres, that is to say the equivalent of 3½ stints in 2003 terms. At night time, quintuple stints may even be envisaged and at Michelin we have effectively worked with this in mind..."
Michelin proposes two types of qualifying tyre, one that enables drivers to put in a second flying lap - should they be slowed during the first by traffic, for example - plus another designed for a single qualifying lap. However, few drivers are able to exploit the latter to its full potential since judicious 'management' is vital, a parameter that explains why it is so often experienced drivers who claim pole-position at Le Mans.
"Getting the most out of a set of qualifying tyres is an art," explains Matthieu Bonardel. "Drivers are invariably amazed by their performance for they allow them to brake 30 metres later and to corner 20 kph 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. The development of these qualifying tyres is carried out during the test sessions we organise with our partners during the year, but it's a tough challenge because there is no other circuit like Le Mans."
One of the main challenges of competing in the Le Mans 24 Hours is the fact that opportunities to test at the circuit itself are few and far between. "Apart from the preliminary practice day, the two qualifying sessions during race-week and the race itself, the circuit is open to ordinary traffic all year round, which makes it practically impossible to test at Le Mans. The preliminary practice session - held this year at the end of April - is therefore extremely important," says Gerard Aussage.
"The track uses trunk roads that are generally very busy, so its surface is highly specific, as is the track's length, 13.6 km. To prepare for this once-a-year fixture we therefore have to turn to circuits that offer equivalent features." This year, Michelin Competition and its partners tested at the Italian circuit of Monza where top and average speeds are also very high. And thanks to their experience, the French firm's technicians were able to extrapolate the data obtained at Monza for the development of their Le Mans range.
Flint and carbon
It is difficult to rule out the risk of punctures at Le Mans. As the race progresses, the track becomes littered with flint dragged onto the track by the cars after visits to the gravel traps. It is also becomes soiled with debris, including fragments of carbon shed by the cars.
"A piece of flint can slice into a tyre at more than 100C like a knife through butter while carbon fragments can be as sharp as razorblades," underlines Gerard Aussage.
The prototypes, which are faster, are more exposed to punctures because they frequently leave the racing line to overtake slower runners. As a result, Michelin, which equips 56% of the cars in this category (LMP1 & LMP2), is more prone to this sort of incident than the other tyre firms present.
"It is slow punctures we fear in particular," says Gerard Aussage. "Along a straight, it is possible for a driver not to notice he has a slow puncture since centrifugal force means that a fall in pressure of 300 g cannot be felt at the wheel. The driver only finds out under braking, or when cornering, and it's too late."
Michelin's partners in the 2004 Le Mans 24 Hours
Alpine-Renault, Porsche, BMW, Peugeot, Toyota, Audi, Bentley. Many of the automobile industry's most prestigious names have placed their confidence in Michelin to help them on their way to the highest step of the podium at Le Mans.
And this year, for the very first time, Michelin will be associated with General Motors and the Chevrolet Corvette C5-Rs in their attempt to secure top honours in the LM GTS category of the celebrated endurance classic. "We worked hard with the Chevrolet team over the winter. At the opening round of the 2004 ALMS championship at Sebring, the Corvettes were 2 seconds a lap quicker on Michelin tyres than they were in the same race in 2003," relates Matthieu Bonardel. "Not only were they faster, but they were above all more consistent and capable of putting in double stints with no fall off in performance."
How many partners? 24 cars from 48 entries (50% of the field)
Who? LM P1 Prototype (9 cars from 19): Champion Racing (N2, Audi R8), Audi Sport Japan Team Goh (N5, Audi R8), Audi Sport UK Team Voloqx (N8 and N88, Audi R8), Panoz Motor Sports (N11, Panoz Elan), Pescarolo Sport (N17 and N18, Pescarolo-Judd), Zytek Engineering Ltd (N22, Zytek), Noël Del Bello (N29, Reynard-Lehmann).? LM P2 Prototype (5 cars from 6): Rachel Welter (N24, WR), Courage Competition (N31, Courage AER), Epsilon Sport (N35, Courage IES), Gerard Welter (N36, WR), Paul Belmondo Racing (N37, Courage JPX) ? LM GTS (5 cars from 7): Corvette Racing (N63 and N64, Corvette C5-R), Prodrive Racing (N65 and N66, Ferrari 550 Maranello), Larbre Competition (N69, Ferrari 550 Maranello) ? LM GT (5 cars from 16): JMB Racing (N70, Ferrari 360 Modena), Luc Alphand Aventures (N72, Porsche 996 GT3), The Racers' Group/Kevin Buckler (N81, Porsche 996 GT3), Orbit Racing/Rodger Hawley (N87, Porsche 996 GT3), Dale White/White Lightning Racing (N90, Porsche 996 GT3).
Michelin tyres for the 2004 Le Mans 24 Hours
How many tyres? 5,700, carried in 18 trailers/semi-trailers.
How many different patterns? Three (dry weather, intermediate, wet weather).
How many different compounds? Four ('soft', 'medium', 'hard', plus one for very warm temperatures) plus two types of qualifying tyre.
How many different dimensions? 10 (according to category and whether front or rear)
How many technical staff? 55
The life of a tyre at Le Mans
Top speed? About 325 kph (before the chicanes and 'Indy' (LM GT: 310 kph before the chicanes and 302 kph before 'Indy').
Maximum lateral G-forces? A peak of 3G before 'Indy', and a sustained 2.8G through the 'Virages Porsche'.
Maximum longitudinal G-forces? 2.5G, under braking for the chicanes
Contact? At 325 kph, each part of the tread of a 65cm diameter tyre hits the ground 44 times every second! Each part of the same tyre hits the ground 6,684 times during a complete lap of the 13.650 km circuit!
Michelin's record at Le Mans
From the historic victory of Andre Lagache and Rene Leonard (Chenard & Walcker) in the inaugural Le Mans 24 Hours back in 1923, to Bentley's memorable one-two finish last year, Michelin's success in the world's most prestigious endurance race spans more than 80 years...
How many wins? 12. 2003 (Bentley), 2002 (Audi), 2001 (Audi), 2000 (Audi), 1999 (BMW), 1998 (Porsche), 1995 (McLaren), 1993 (Peugeot), 1992 (Peugeot), 1989 (Sauber), 1978 (Alpine-Renault), 1923 (Chenard & Walcker)
How many consecutive wins? Michelin tyres have won the Le Mans 24 Hours overall every year since 1998
Michelin's result in the 2003 Le Mans 24 Hours
Overall victory with the Bentley of Kristensen/Capello/Smith, Victory in the LMP900, LMP675, LM-GTS and LM-GT classes with Pirro/Lehto/Johansson (Audi), Andre/Maury-Laribière/Pillon (Reynard-Lehman), Kox/Enge/Davies (Ferrari) and Luhr/Maassen/Collard (Porsche) respectively. Michelin runners monopolised the top-ten positions overall in the final classification.