WRC

Argentina: Michelin preview

After the recent adrenalin rush generated by a Cyprus Rally steeped in drama and leaderboard changes, the WRC's regulars have crossed the Atlantic Ocean for Argentina intent on picking up where they left off mid-April. For sure, Marcus Gronholm...

After the recent adrenalin rush generated by a Cyprus Rally steeped in drama and leaderboard changes, the WRC's regulars have crossed the Atlantic Ocean for Argentina intent on picking up where they left off mid-April. For sure, Marcus Gronholm and Peugeot

Michelin will be out to repeat their Cypriot triumph, but their rivals will be looking for just one thing: revenge. In light of the clear progress made by the teams on gravel since last year, one thing looks certain: this weekend's battle in the Andean foothills promises to be as fierce as ever!

Right up to the chequered flag, the Cyprus Rally had us holding pour breath. To the end, the final outcome could hardly have been more uncertain before Peugeot's Marcus Gronholm and Richard Burns took command for good on the final loop of stages. Their reward: a fourth consecutive one-two for the 206 WRC-Michelin that has seen the French machine pull clear at the top of the Manufacturers' points table.

Yet despite appearances, Peugeot's appreciable cushion has in no way put a damper on the suspense. On the contrary, the Cyprus thriller could well prove to have been a mere foretaste of further titanic showdowns to come over the next four gravel rounds, beginning with the Rally of Argentina that takes place in the picturesque sierra around Villa Carlos Paz in the north-west of the country.

It is no secret that the championship regulars have a soft spot for this annual flyaway to Latin America. Indeed, the rally could hardly wish for a more splendid backdrop, while every year it sparks off a contagious fervour amongst the local population. But perhaps more than anything else, it features some of the most daunting classic tests of the calendar; stages with such evocative names as 'El Mirador' or 'El Condor' and that take crews to altitudes in excess of 2,200 metres. This isn't one for the faint -hearted!

Meanwhile, Michelin's objective on this exploit-promoting terrain will be to return to its winning ways on the sole WRC fixture that has escaped it in the last 24 months. And with Hyundai, Mitsubishi, Skoda and defending champs Peugeot as its partners, that's a challenge the firm is clearly poised to rise to with its customary rigour and commitment...

On the technical front

Michelin ATS: 15 years already

Inside a WRC tyre, it's air of course that plays the leading role. But all stars have their stand-in, ready in the wings to take over in an emergency. In the case of a WRC tyre, this function is filled by Michelin's ATS system (Appui Temporaire Souple, or Temporary Flexible Support). Used for the first time in Greece in 1987, it will celebrate its 15th anniversary in world class rallying in May. A timely opportunity to recall how it works and to answer some of your frequently asked questions…

The Michelin ATS system: how it works

Phase A: The unassuming 'doughnut' of flexible foam that makes up the ATS system is in fact a highly sophisticated piece of technology, notably the make-up of the gas that fills its micro-cavities. Michelin's fitters slide the mousse inside the tyre before fitting the cover to the rim. So long as the tyre hasn't been inflated, the insert takes up all the space inside.

Phase B: When the tyre is inflated to its working pressure of approximately 2 bar, the mousse is compressed; its volume is roughly halved. For the moment, the insert is cold and therefore inactive, ready to be fitted to the car and tackle the stage.

Phase C: Once the stage has started, the heat generated by driving at speed transforms the physical properties of the mousse. The ATS system is now primed and capable of withstanding the sort of dynamic loads all rally tyres must soak up. So long as everything goes according to plan 'on the outside', the system remains inactive, but it is ready to intervene at the slightest alert.

Phase D: In case of air loss (because of a cut, a hole or, very often, a damaged or broken rim!), the system is instantly deployed. With air pressure no longer compressing it, the insert automatically expands to fill the inside of the tyre. Thanks to its special properties, notably its flexibility, the mousse perfectly takes over the role of the air that has escaped.

Phase E: The system has been deployed, but the driver is able to continue the stage without having to stop to change the wheel. And in the majority of cases, he can carry on driving as hard as before. It is frequent that he doesn't even realise he has punctured, especially on gravel. Fastest times set after the system has been activated are not rare. Nor are examples of drivers going on to win the rally thanks to the Michelin ATS system!

Five frequently asked questions concerning the Michelin ATS system

1, How much does an ATS mousse weigh?

According to its dimension, each mousse weighs around 2kg.

2, How much does an ATS mousse cost?

As for the tyres, it is difficult to put a precise value on a mousse insert since the ATS system is an integral part of the global service Michelin provides its partners. Having said that, given the important contribution it can make to their success, the cost is negligible. For the record, Michelin produced a total of some 10,000 ATS inserts for the 2001 season.

3, Is the Michelin ATS system fitted systematically?

Michelin's system is today available for the full spectrum of tyre dimensions and types of surface encountered in the World Championship. With the odd exception, it was even used successfully by Michelin's partners throughout last year's Safari Rally (Michelin 1-2-3), the specific constraints of which (heat, long portions covered at high speed, punishing terrain) had for a long time restricted its use to the shorter stages.

4, Can a mousse that has already been fitted be used again?

Yes, so long as it hasn't actually run on the car. By definition, the mousse is heat sensitive. This is why the inserts are always stored in the shade, or even in refrigerated trucks at the hottest venues.

5, Why is the ATS system used only on WRC cars competing in the World Rally Championship?

The use of mousse tyres in national championships was outlawed by the regulations at the end of the 1990s. The governing body also decided not to run this type of system when drawing up the regulations for the recently created FIA Junior World Championship

-michelin-

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About this article
Series WRC
Drivers Richard Burns , Marcus Gronholm