HOW DOES IT WORK?
With the Pax System, Michelin has once again succeeded in extending tire performance limits, just as it did with both the radial and the green tire. The new technology involves an inseparable assembly.
Much more than a tire, it is a complete system. It is comprised of a tire with an entirely new architecture, a wheel, an internal support ring and a run-flat detector.
Today, balancing all the performance areas of Michelin tires has reached a very advanced stage, and with the current design significant progress is increasingly difficult to obtain. According to use, one performance area can always be given more or less priority, but the overall balance is no longer advancing in any really significant way. So how can any new breakthroughs be made? With the current shape of tires and wheels, the anchoring area is composed of the tire bead and a transitional zone. The bead, which is very rigid, serves to anchor the tire onto the rim; and the transitional zone provides the link between the bead and the sidewall.
When the tire is running, distortions in the transitional zone consume energy and interfere with the function of the sidewall, particularly when there are lateral forces. The challenge consisted of completely dissociating the sidewall and anchoring functions to make each of them more specialized and to optimize their performance.In the Pax System, the new anchoring system locks the tire onto the rim, and the transitional zone with the sidewalls is no longer required. The result is that the sidewall function is no longer disturbed.
PAX SYSTEM PERFORMANCES
Conventional performance improved
By only keeping the ”useful” part of the sidewalls, rolling resistance is 10% lower. This also brings down heating by the same amount and therefore reduces energy consumption.
Benefits: less fuel consumption, environmental protection.
Shorter sidewalls and better-optimized overall architecture give improved steering. Vehicle handling is more precise.
Benefits: security, better cornering, and easier handling.
The load capacity / dimensional balance has been altered.
Benefits: this extra space can be used to advantage for security and capacity improvement.
No unseating; The Pax System tire is designed not to unseat, even with a sudden loss of pressure. The “clipping” of the tire onto the rim and the design of the bead insure its hold on the rim in virtually all circumstances. Combined with the support ring and the run-flat detector, this feature allows the driver to continue at zero pressure at a speed of 80 km/h for a distance of up to 200 km. The spare wheel becomes unnecessary.This additional space opens up new technical and aesthetic design opportunities for the vehicles of tomorrow.
• Active security, better control of the vehicle in virtually all circumstances, even with a sudden loss of pressure.
• Passive security, the reassurance of not being immobilized by sudden pressure loss.
Choice of where to stop for repair:
• Elimination of the spare wheel giving more internal space or more accessories.
• New technical and styling design possibilities for new generations of vehicles.
This additional space can be exploited by automotive designers in one of two ways:
• they can either use the extra space released within the wheel(to fit bigger brakes, for example).
• or they can use the smaller overall dimensions of the wheel and tire assembly (to release extra space within the vehicle, for example).
THE COMPONENTS OF THE PAX SYSTEM
The tire: It still provides the essential tire functions: mobility, steering, torque transmission, shock absorption, load carrying, and durability.The anchoring area is reduced to a compact ”anchoring point”. The sidewalls are short and rigid. They provide improved steering while ensuring a high level of comfort. They are just high enough to provide good flexibility. Moreover, it is one of the most visible features of the Pax System -a lower tire for the same load capacity.
The wheel: The wheel is designed as a single unit in steel or alloy, and apart from its conventional role of supporting the tire, it also includes the support ring and the run-flat detector. Wider and with a larger diameter than an equivalent standard wheel, it has two different seats and offers new styling possibilities.The support ringMade from an injected elastomer, it slides onto the rim and supports the tire when there is pressure loss in the fitted assembly. Its load capacity enables a long distance to be driven at zero pressure in complete safety.
The run-flat detector: The detector uses a special frequency to signal contact between the tire and support ring. The close interaction of these four components demands very accurate assembly. Technical adaptations to individual and semi-automatic machines have had to be developed.A special point of anchoringIn conventional anchoring systems, pressure forces are applied from the inside of the tire towards the outside and squeeze the tire against the rim flange.The new anchoring system uses mechanical locking and all forces acting on the tire produce a tension in the carcass that reinforces this locking.