Michelin PAX System - Prior To The Michelin PAX System

Prior To The Michelin PAX System

Prior to the late 1990s introduction of the Michelin PAX System run flat technology, both Michelin and Goodyear had introduced the a "zero pressure" run flat technology, meaning that a pneumatic (air pressure supported) tire could support itself with no air pressure. The new zero pressure tire was a modified standard tire, constructed with a sidewall that was much stiffer and heavier, so as to support the weight of a car running at speed without careening out of control. The heavier sidewalls and special bead construction allowed a driver to drive a car with little or no air at a limited speed (approximately 50 mph) over some specified distance to a service station, or at least off the roadway out of immediate danger. Consider that in a conventional pneumatic tire, loss of pressure at speed would result in the collapse of the soft tire sidewalls such that the metal wheel edges would slice through the collapsed sidewalls. This would likely result in an accident, possibly fatal, as well as the destruction of the tire, and possibly the wheel.

The reinforced sidewall Goodyear EMT (Extended Mobility Tire) was introduced with the 1994 Chevrolet Corvette. Michelin also introduced a similar tire in the mid-1990s called the Zero Pressure System, and the ZP designator differentiates this type of run flat tire from a conventional tire.

Such tires required the introduction of a Tire Pressure Monitoring System, sensors and instrumentation in the car, which would indicate to the driver a condition of dangerously low tire pressure. Prior to the reinforced sidewall zero pressure run flat type tires, the driver could tell when a conventional tire was going flat. This low or no pressure condition was almost impossible to detect by the driver with a zero pressure run flat, until the tire failed.