Michelin PAX System
| Company type | Technology system |
|---|---|
| Industry | Automotive, Tire manufacturing |
| Founded | 2000 |
| Founder | Michelin |
| Defunct | 2008 |
| Fate | Discontinued due to low market demand |
| Products | Run-flat tire system |
| Parent | Michelin |
PAX represented an innovative run-flat tire technology developed by Michelin during the 2000s. This system utilized a unique combination of a specialized rim and tire, allowing vehicles to continue driving temporarily after a puncture. At its core was a semi-rigid support ring affixed to the wheel rim, which upheld the tire and sidewall structure, enabling limited-speed emergency travel until the tire could be replaced.
The PAX system was installed on a diverse array of vehicles, ranging from high-performance supercars like the Bugatti Veyron EB 16.4, luxury automobiles such as the Rolls-Royce Phantom, to more conventional models including the Honda Odyssey and Nissan Quest.
Early Innovations
Prior to the advent of PAX, both Michelin and Goodyear had introduced pneumatic tires featuring reinforced sidewalls designed to temporarily support a vehicle’s weight when air pressure was lost. These tires incorporated thicker sidewalls that permitted driving at reduced speeds—approximately 50 mph—to reach repair facilities, thereby minimizing accidents caused by sudden tire deflation.
Because these reinforced tires did not visually indicate low pressure, electronic tire pressure monitoring became necessary. Goodyear’s Extended Mobility Tire (EMT) was first introduced on the 1994 Chevrolet Corvette, while Michelin launched its Zero Pressure System ("ZP") in the mid-1990s.
Introduction and Market Launch
The development of PAX commenced in the late 1990s under the initial name "pneu accrochage vertical" (PAV). The technology was publicly demonstrated between 1997 and 1998 before being officially branded as PAX in November 2000. Distinct from earlier run-flat solutions, PAX integrated a specially engineered wheel, an internal support ring, and a custom-designed tire into a cohesive system.
PAX made its European debut on the 2002 Renault Scenic and entered the American market equipped on the 2004 Rolls-Royce Phantom.
Termination of Production
In December 2007, Michelin announced it would halt further development of the PAX run-flat system due to lower than anticipated market demand; however, production of PAX wheels and tires continued for existing vehicles. By April 2008, Michelin ceased manufacturing PAX components altogether.
Legal Proceedings
In March 2007, a federal class-action lawsuit was initiated against Michelin and American Honda Motor Company by owners of Honda Odyssey and Acura RL models fitted with PAX tires. Plaintiffs from various states alleged that PAX tires exhibited shorter durability compared to standard tires, were susceptible to wear and sidewall punctures, required servicing exclusively at limited authorized centers, and incurred high replacement costs. The lawsuit also contended that repair expenses and convenience were misrepresented by the manufacturers. This case was consolidated with other similar lawsuits in March 2008; two additional suits were dismissed.
A settlement was reached in December 2008, extending the original warranty coverage to 36,000 miles for vehicles originally equipped with PAX tires. The agreement mandated continued use of the PAX system on affected vehicles and included reimbursement provisions for spare tire kits provided by Honda. However, specifics regarding compensation for trip interruptions and one-day replacement guarantees remained unclear due to the scarcity of PAX-certified service locations. The deadline for class claims was set for January 2010.
On December 20, 2010, final approval of this consumer class action settlement was granted by the U.S. District Court for Maryland.
Technical details
The PAX system presented an innovative approach by combining an asymmetric wheel, a supporting insert, and an asymmetric tire to provide run-flat functionality for distances up to 125 miles at speeds of 50 or 55 mph.
Although the overall weight of a PAX assembly was approximately equal to that of four standard tires plus a spare, it added to the rotating mass and unsprung weight, which could influence vehicle dynamics. Nevertheless, vehicles outfitted with PAX eliminated the need for a spare tire, thus balancing total weight and creating additional storage capacity. Michelin projected that retail replacement expenses would be similar to purchasing five conventional tires, with actual costs ranging from US$1200 to $1600 for models such as the Odyssey in 2008—exceeding the price of some traditional tires. Reports suggested that PAX tires offered a more comfortable ride and improved fuel economy, although user experiences varied. Despite advantages in safety and mobility, limited availability and higher service costs impacted consumer satisfaction. A tire pressure monitoring system (TPMS) was compulsory for vehicles equipped with PAX tires, coinciding with the broader industry adoption of TPMS shortly thereafter.
Contrary to standard run-flat tires that rely on rigid sidewalls, PAX tires utilized soft sidewalls designed to collapse when deflated until the vehicle’s weight rested on an internal polymer support ring mounted on an asymmetric wheel. This configuration secures the tire firmly onto the wheel during operation, preventing separation while cornering or at high speeds. The outer diameter of the wheel is smaller than the inner diameter facing the suspension, and a lubricating gel coats the support ring to enable smooth rotation even when the tire is flat.
PAX tires are repairable from the inside much like conventional tires; if replaced without damage to the support ring, that component does not require substitution. Typically, a fresh gel pack is applied during maintenance.
The sizing system for PAX tires uses only metric units—for instance, a PAX tire marked 245-680R460A specifies a tread width of 245 mm, an overall diameter of 680 mm, radial construction ('R'), a wheel seat diameter of 460 mm (approximately 18.1 inches), and 'A' indicating an asymmetric wheel design.
Servicing PAX tires demands specialized tools and technician training. Michelin committed to providing replacements within 12 hours if dealers were unable to repair or stock them. Partnerships with Honda (Odyssey) and Acura (RL) ensured that dealer inventories included complete wheel-tire assemblies; however, Canadian versions of the Odyssey did not offer PAX options.
To prevent proprietary supply challenges experienced with the earlier TRX tire, Michelin licensed PAX technology to other manufacturers including Pirelli, Goodyear, Toyo, and Sumitomo. Despite these agreements, no other companies manufactured tires compatible with the PAX system, effectively leaving Michelin as the sole supplier for consumers.
United States
- 2004–2008 Rolls-Royce Phantom
- 2004–2011 Bugatti Veyron
- 2005–2009 Honda Odyssey Touring
- 2006–2008 Acura RL
- 2006–2007 Nissan Quest
Europe
- Bugatti Veyron EB 16.4
- Renault Scenic models—launched February 2002
- Audi A8—introduced November 2002
- Rolls-Royce Phantom—debuted January 2003
- Audi A4—released September 2004
- Mercedes-Benz S-Class
- BMW 7-Series (G70)
- Lancia Thesis Blindata B6