From European Rubber Journal comes word that Michelin has stopped further research on the PAX run-flat tire system.
Philippe Denimal, research director at the Group’s Technology Centre, told ERJ, “Today we do not intend to develop a new PAX simply because there is no big market demand. The market demand is insufficient to justify the expense.” He added, “PAX is a long story for us. When we launched it, we were hoping for a big market development. In fact the real market for zero pressure tyres is limited to some small percent of total sales in Europe. ” (ERJ online, November 12, 2007)
The news does not come as a surprise to those of us who follow the run-flat tire market. The PAX system was introduced in 1998 (a precursor, called PAV, was introduced in 1996), and at the time of its introduction many in the tire industry expected it to become the industry standard for run-flat tires, given its functional advantages and Michelin’s aggressive marketing, which included creating high profile partnerships with other tiremakers.
PAX truly is a system, encompassing a customized wheel and tire, a flexible internal support ring, and a tire pressure monitoring system. PAX is a support ring system, which means it relies on an internal ring to support the tire in the event of air loss. It offers continued driving for at least 200 kilometers at 80 km/h at zero pressure, which is considerably farther than most self-supporting run-flats, which typically offer about 80 km at zero pressure. PAX also offers a higher load capacity than most self-supporting systems. The main drawbacks to PAX are its high cost and the fact that it requires a customized rim. Though the PAX system gained some high profile fitments (including Rolls Royce), automakers were reluctant to adopt it based on its high cost and the requirement for a customized wheel. PAX is also a rather complex system, so mounting the tires properly requires specialized training and equipment, which adds to costs and limits the number of shops that can handle the tires.
Rather than PAX, the auto industry instead has adopted self-supporting run-flats where it chose to mount run-flats at all. Self-supporting run-flats rely on reinforced sidewalls to support the tire in the event of pressure loss. According to Prospects for Run-Flat Tires, a Notch Consulting report published in February 2007, support ring systems held about 5% of the total market for run-flat tires in 2006, while self-supporting types held 94%. Michelin also offers self-supporting run-flats under the ZP tradename. Conti offers a competitive support ring technology (CRS, or ContiSupportRing) that can be used on conventional rims and with all tires.