Michelin tire testing notes

WORLD RALLY CHAMPIONSHIP TYRE TESTING Competition tyre testing at its most complex In 2001, as part of a cost saving package for world class rallying, the FIA introduced a ban on all testing outside of Europe, a measure that has had a direct ...


Competition tyre testing at its most complex In 2001, as part of a cost saving package for world class rallying, the FIA introduced a ban on all testing outside of Europe, a measure that has had a direct incidence on the way tyre manufacturers prepare for so-called 'flyaway' rounds. The combination of this restrictive regulation and the particularities of rallying (variety of terrains, changeable conditions, etc.) means that tyre testing is much more complex when it comes to rallying than in any other form of motor sport. After Michelin's one-two finish in Monte Carlo, with Sébastien Loeb (Citroën) and Toni Gardemeister (Ford), and its podium in Sweden, again courtesy of Gardemeister, the French tyre firm travels to Rally Mexico as leader of both the Drivers' and Manufacturers' championships.

The South American event is not only the first gravel round of the 2005 championship but it is also the first 'flyaway' fixture of the year. And before the series returns to Europe for late April's Rally Italia Sardinia, which kicks off a succession of Mediterranean rim events, the WRC will have visited a second southern hemisphere round on the opposite side of the planet, Rally New Zealand (April 8th-10th). In addition to the fact that they both take place on the loose, the next two WRC rounds (Mexico and New Zealand) share another point in common: the fact that all on-site pre-event testing is banned, with the exception of the short shakedown run organised the day before the start. But while this session can sometimes be useful for drivers looking to fine-tune the set-up of their cars, it in no way serves as a tyre test in the accepted sense of the term. Indeed, tyres used during shakedown must now come out of the quota nominated by the drivers for each event, as must certain mechanical components, a factor that can incite teams to keep the number of passes they perform over the test stage to a minimum with a view to saving the engine and tyres for the rally proper.

Today's World Rally Car regulations are particularly restrictive and conservative and tend to serve as a brake as far as car development is concerned. The contribution that tyres can make to obtaining performance gains is consequently decisive in the evolution of the car/tyre package.

"Even so, following a gentlemen's agreement between the two tyre firms involved in the WRC, we voluntarily restrict the proportion of work committed to tyre development proper to something like 15-20% of the total distance covered by drivers in testing," confides Michelin Competition's Rallies Manager Aimé Chatard.

"And for cost reasons, we endeavour to do tyre tests at the same time as the car tests. A hundred tests a year A typical test session generally lasts three days, two of which are given over to tyres and it is only once the car's set-up has been optimised that the driver starts the actual tyre part of the programme. On average, Michelin will take three new solutions which are evaluated in comparison with a benchmark product.

"This work is followed by a debriefing session with the drivers, engineers and Michelin's technical staff to decide which solutions will be taken to the event in question. Michelin technicians and fitters attend every test but the service we provide our partners doesn't stop there. To cater for possible changes in weather conditions during the test, we always have a full range of tyres with us.

"For example, if the test session is planned for hot, dry ground, we will also carry a selection of products that we can run should the weather take a turn for the worse. In that way, we can improvise a test for a round scheduled for the back-end of the season when the conditions tend to be less stable," says Aimé Chatard.

"In 2004, Michelin took part in a hundred or so test sessions, which works out at an average of about two sessions every week. For any given rally, drivers will get through as many tyres in testing as they do during the event itself, that is to say about fifty. Each of Michelin's partners arranges and organises its own tests individually.

"This is one of the specific features of rallying compared with Formula 1, say. In F1, it is common for a number of teams to test at the same venue on the same day. This is inconceivable in rallying, if only because the test stages evolve after every pass. In rallying, each test is unique."

Locating representative test stages The regulations concerning testing are particularly draconian (Article 13.2.2): while unrestricted work is authorised in France, Great Britain, Spain, Italy and the Czech Republic, a four-day upper annual limit is enforced in Finland, Sweden, Greece and Germany and testing is simply forbidden everywhere else. For 2005, this means that on-site preparation is outlawed for half the events that make up the calendar, namely Mexico, New Zealand, Turkey, Cyprus, Argentina, Japan and Australia.

"The last time we tested on another continent was in Kenya in 2002, the last year the Safari Rally was held. Today, we tend to favour Spain, where there are plenty of good bases suited to preparing for the majority of gravel rallies that take place outside of Europe."

Such locations extend from the north of the country to Malaga. "It is clearly impossible to find somewhere that is absolutely identical to the terrain of each rally. The challenge is to find somewhere that is as representative as possible."

The stages in Mexico tend to be wide, hard packed with very little rutting and it is effectively possible to find similar conditions in Spain. However, another particularity of Rally Mexico is the exceptionally high altitude to which its stages climb (more than 2,000 m, peaking at 2,737 m). It is impossible to find suitable roads for testing this high up in Spain.

"We therefore have to extrapolate the results we obtain. Spain also offers test stages which resemble the narrow, averagely hard roads found in New Zealand. But in this case it's impossible to replicate New Zealand's notorious thick surface layer of gravel which tends to penalise the first cars through the stages when conditions are dry and through which tyres must cut in order to find grip."

For new events to the calendar organised outside of Europe, as was the case with Mexico and Japan in 2004, the banning of overseas testing obviously represents a handicap.

"This regulation is contrary to Michelin's spirit which is based on a methodical, rigorous approach. The record books show however that our tyres have frequently helped our partners win when the championship visits a new event for the first time, as in Turkey in 2003 (Sainz, Citroën-Michelin) and in Mexico last year (Märtin, Ford-Michelin).

"True, Michelin had been associated with the Peugeot 206 WRC of Rovanperä which won the 2002 Rally Mexico (Peugeot had entered the Finn to scout the event prior to its inclusion in the World Championship) but the relatively low pace of that year's competition offered little opportunity to gather valuable information (Harri completed the distance with a cushion of half an hour over his closest chaser). For this year's event, we were able to use the data from 2004 when the fight was significantly fiercer to establish two main lines of work: the effect on tyre wear of the fall-off in engine power due to altitude and the favouring of progressive lateral rear-end grip over the wide stages that tend to favour drifting. Given this restrictive regulation, the ideal situation for us would be to at least have the chance to stay on in the country after the event for testing purposes."

Test stages When preparing for non-European rounds, the extremely strict regulations mean that the main challenge is to locate test stages that are as representative as possible of the actual lie of the land. For safety reasons, the roads used by Michelin and its partner teams need to be closed to traffic which entails obtaining authorisations from the local administrative bodies. A number of privately-owned permanent testing venues also exist, such as Alès and Château-Lastours in the south of France. Spain and Italy too are very popular with the WRC teams.

Dramatic reductions To keep a check on costs in the World Rally Championship, the FIA has introduced rules concerning testing for events that take place outside of Europe. In collaboration with the tyre companies, it has also placed an upper limit on the numbers of tyres crews may use during each round. In 2005, drivers will run an average of 40 tyres per event, compared with close to 200 in the early 1990s! Back in those days, Michelin could turn up with a type of tyre for practically every stage as a function of both the surface type and temperature. In the light of today's formats and also the quota system, a given tyre now must cover a temperature range of something like 10 to 15°C. Just two types of tyre effectively need to cover the full range of temperatures likely to be encountered during a full day of competition. Our priorities today are flexibility, performance and endurance," underlines Aimé Chatard. And that's no mean challenge!


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About this article
Series WRC
Drivers Sébastien Loeb , Toni Gardemeister
Teams Citroën World Rally Team