Enormous Pressure

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Rally competitions cover a wide variety of terrains. That is why the range of tyres BFGoodrich provides for its teams must be very versatile.

Asphalt, dirt and snow are the favorite playgrounds for drivers, teams and tyres… These three types of surface demand maximum attention, especially when you realize how long a rally tyre lasts…. rarely more than 80 km (50 miles). To produce a tyre that combines long life, robustness and strength… requires the work of a whole team of extremely skilled and qualified people: chemists, developers, technicians…

They all have one aim in mind: victory! Some fifteen people travel to the location. Around 1500 tyres are taken to each rally in five semi-trailers.

At each rally, there are :

The developers & chemists

These are the people who create or improve competition tyres. The BFGoodrich developers and chemists regularly go to test sessions and rallies to study the behavior of the products, the type of surface, etc.

The management

Michelin Competition is managed by Frederic Henry-Biabaud and combines all of the Group’s Competition business (MotoGP, Endurance, Rallying) and the “Marketing & Sales” department which controls all the trade sales of competition tyres (IRC and national rallies, Long-distance Rallies, Race tracks, etc.). Matthieu Bonardel is Michelin Competition 4-wheel Business Manager (Endurance + Rallying) and Jacques Morelli is IRC Program Manager for BFGoodrich.

The fitters

It is their job to fit tyres on wheels and remove them before and during the competition. Some fitters also drive the semi-trailers and set up the BFGoodrich “pits” a few days before the rally begins.

The technicians

Three BFGoodrich technicians are made available to Intercontinental Rally Challenge partner teams. They advise the drivers and engineers on the use of products and the choice of tyres. Between rallies, they take part in various test sessions.

BFGoodrich tyres and Long-distance Rally competition

Because many drivers choose their tyres for the performance and the feel they provide, BFGoodrich has developed specific products for each type of surface, thus maximizing the vehicle’s traction.

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Traction on loose ground is a typical example for analyzing the vital role of tyres on a long-distance rally. This highlights the importance of the inflation pressure, whether this is controlled by an automatic system or manually. On loose ground, the tyres dig deeply into the dirt, pushing the sand ahead of them and creating ruts as the vehicle advances. The effect on the vehicle is like going uphill; the rolling resistance being approximately 50 times greater than on hard flat ground.

Therefore, in order to make better progress on loose ground, this digging in must be reduced, to minimize the rolling resistance. This is the “flotation” principle. Thus, to increase the capacity of the tyres to carry a load, it is necessary to reduce their inflation pressure.

Baja T/A Sand tyres have been specially designed to improve traction in these conditions :

  • The choice of the right tyre structure makes it possible to maximize the load distribution on the tyre and the pressures over the area in contact with the ground.
  • The shape of the contact patch is also important: longer and narrower is better for mobility on loose ground. That is why Baja T/A Sand tyres are rather narrow with high sidewalls (unlike tarmac sports tyres which are wide with low walls).
  • The tread pattern will give the extra traction required for the vehicle to move forward faster. In conclusion, the tire pressure is the most important factor in the performance of competition vehicles on loose ground. This is optimized by constantly adapting BFGoodrich tyres to the special demands of long-distance rally competition, and everyday extreme use for sensational driving.

 

On-board tyre pressure control system

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High temperatures… Sustained high speeds… Heavy vehicles…

Tyre pressure control is important, both for safety and performance.

Being able to check the tyre pressure easily gives a performance advantage when crossing dune areas. For example, a competitor will benefit by lowering the tyre pressure by around 1 bar, in order to increase the area of contact with the ground and improve his off-road capability.

On the other hand, it is essential to return the pressure to 2.2 or 2.4 bar as soon as the vehicle encounters a harder surface. Some competitors may be tempted to maintain a low pressure to provide more comfort and a slight improvement in performance.

It is therefore important to be able to adjust the pressure of the tyres in the field, wasting as little time as possible. Jean-Louis Schlesser was the first to invent a system for his two-wheel-drive buggies to check and adjust the tyre pressures from the cockpit.

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Controlled by the co-driver, this system also improves safety.

In the case of a slow puncture, it is possible to maintain enough pressure in the tyre to continue driving.

The principle is simple: a detection system installed in the wheel measures the inflation pressure.

An indicator on the instrument panel enables the co-driver to monitor the “health” of his tyres; he can control the pressure via an external tube which connects the tyre valve to an on-board pump

BFGoodrich tyres and Rally competition

With its partners, BMW, Nissan, Mitsubishi, Volkswagen, the Schlesser-Ford buggies and the Protrucks…

Every year BFGoodrich proves the quality and the endurance of its tyres.

On asphalt, gravel and snow, with Citroën, Ford and Subaru, BFGoodrich very quickly became WRC world leader (until 2007) and has won two consecutive world champion titles.

As they are the only points of contact with the ground, the more varied and hostile the terrain, the more crucial the role of the tyres.

This is because the tyres must provide several functions simultaneously :

  • Bear the weight of the automobile. In some cases – when hitting a bump for example – one tyre may have to support more than three tons!
  • Steer and provide changes of direction.
  • Cling to surfaces that do not usually provide much grip.
  • Last.
  • Reduce shocks while providing the final link in the chain of road-holding components.

 

And yet some people still think that tyres are just round, black things…

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