Articles on Runflats and PAXSystem ...
December 2000
Reinventing the wheel
Will run-flat tires replace radials?
BY EDMUND CHEW
When you see one automaker put a feature on a concept car, industry observers might shrug. When eight concept cars feature the same option at the same show, they begin to see a trend.
That was the case at the Paris auto show in September, where six show cars featured Michelin Pax run-flat tires. The French tire maker is promoting the Pax as a new global standard for run-flats. The tires were on three vehicles from Citroen, as well as cars from Peugeot, Renault and Pininfarina. As if to emphasize the trend, Cadillac announced in October that its future roadster will feature Pax tires in 2002.
Tire manufacturers dream of replacing radial tires with run-flats as the auto industry's tire of choice. To do so, three major tire makers have formed a consortium to promote Michelin's Pax tire as the industry standard. Goodyear Tire & Rubber Co. and Pirelli S.p.A. have adopted Pax, and other tire makers may join them. The consortium "is going to result in faster progress than if the companies had gone their separate ways," said Saul Ludwig, managing director for McDonald In-vestments Inc. in Cleveland, Ohio.
But that will not ensure quick success, Ludwig adds. For the next five years, few automakers will adopt run-flat tires as original equipment, he said. "Each year we will see a little more. If you look out five to 10 years, there is a possibility for a fairly large shift to run-flat tires."
NICHE SUCCESSES
Automakers prefer to start small. Run-flats are on a few low-volume models, such as the Chevrolet Corvette and an armored version of the Mercedes S class. In 2001, Audi will introduce a niche model with run-flats, and Renault will unveil a mid-market offering. Nissan also will market the run-flat tires in the future, although details are confidential.
So far, Goodyear has sold more than 300,000 run-flats, which it markets as the Extended Mobility Tire. Continental AG and Michelin also sell aftermarket run-flats. But these tires have not gained a major share of sales. That is why the tire makers are courting the automakers. "To be successful, a run-flat tire must be accepted by the car makers as original equipment," said Richard Ahsbahs, Michelin's head of Pax development for the European market.
The Pax system features a tire with a shallow sidewall that does not separate from the wheel when it deflates. If a sensor detects an unusually low tire pressure, an instrument panel display alerts the driver. The motorist can drive on the tire for about 200 kilometers before stopping at a repair shop to fix it.
Michelin started work on the new tire in 1995 and began marketing the tire to automakers in 1998. Other tire makers grew interested. Last year, Pirelli signed a joint technology agreement with Michelin. In June, Goodyear approved a joint venture with Michelin to develop the Pax system. That deal brought together three manufacturers that produce more than half of the world's tires. Now, wheel manufacturers such as Amcast-Speedline, Montupet and Ronal are working with the tire companies to develop the new wheels for Pax.
LOW CONSUMER DEMAND
But winning automakers' acceptance has been slow work, particularly in the absence of strong consumer demand.
To some extent, tire makers' success in making tires more sturdy - and flats less frequent - has complicated the case for run-flats. Japanese statistics show that in 1976, one flat tire occurred every 41,000 kilometers. By 1998, the failure rate declined to one in 72,000 kilometers, according to Japan's Automotive Industrial Association. In the United States, a J.D. Power survey released in November ranked run-flat tires tenth among the safety features that consumers seek.
"I don't think the consumer is aware yet of the real benefits," says David Leone, chief engineer for the Cadillac luxury roadster. "As automakers begin to provide them, I think there will be more awareness. Peace of mind is something that customers will really appreciate."
But for now, customer indifference and low aftermarket sales have prodded tire makers to seek original-equipment status. To win acceptance of run-flat tires, tire makers must ensure that their performance can match that of conventional radial tires under normal conditions. Remy Quentin, Pirelli's tire business development manager, says that goal is easier to achieve when designing tire models as original equipment for specific cars.
Quality of ride was a key consideration for Cadillac, Leone said. Pax and its competitors have comparable performance when flat, he said, but Pax provides the smooth ride needed for a luxury car when fully inflated. That's because the tire does not need a rigid sidewall for support if the tire loses air. Instead, a plastic ring inside the tire supports it if the tire goes flat.
Tire companies must satisfy automakers on two other key criteria: weight and price. Weight has become an important selling point. Michelin's marketers note that the Pax tires can save weight because automakers no longer need a spare tire and jack. That compensates for the extra weight of a Pax tire.
WEIGHT REDUCTION
Three years ago, the Pax tire and wheel were 75 percent heavier than a standard wheel and tire. To reduce weight, Michelin worked with Dow Chemical Co. to design a polyurethane support inside the tire. Now the Pax tire and wheel is only 12 percent heavier. Because a spare tire no longer is necessary, the run-flat tires offer a net weight reduction, Ahsbahs says.
But the big leap forward will come when automakers design new vehicles using the new standard, says Frank Philpott, Goodyear's chief Pax engineer in Luxembourg. Then, automakers could exploit Pax's space-saving potential by designing floorpans that do not incorporate space for a spare tire.
"If you design from scratch without the spare wheel, you have more design flexibility, more space and a lower weight," Philpott said.
One concept car at the Paris show, the Kion by Johnson Controls Inc., demonstrated the tire's space-saving benefits. Designers lowered the floor of the trunk by 60 millimeters, allowing easier access and a simplified design for the trunk floor. Anthony Grade, head of car design for Renault SA, uses Pax as an option on the Twingo model. But the lack of a spare is not an unalloyed benefit, Grade says.
CRUMPLE ZONE
"We have found that consumers are not ready to give up on the spare tire yet; they want the security of having a spare," he said. "Finally, in pure design terms, the Pax system does give us options in terms of trunk space. But actually the spare tire well forms part of the crumple zone in the rear of the car - it serves an engineering and safety purpose, and this is something we have to consider."
Michelin claims that the cost of four Pax tires is the same as a conventional five-wheel setup. But the sensor system that alerts drivers to low tire pressure adds about $200 - which is the upper limit of what U.S. consumers told the Power survey they would pay for run-flats.
Howard Smith, a car analyst with Baring Securities in Japan, said the run-flat tire may have difficulty becoming popular with the Japanese public because of the extra price. "The market is driven by price more than function," he said.
NEW EQUIPMENT
Price is not strictly a consumer issue, either. Auto dealers, service stations and tire stores would have to invest in special equipment to handle Pax tires and wheels.
Although no Japanese automakers have announced plans to use run-flats as original equipment, run-flats were well received at the 1999 Tokyo auto show with the unveiling of Mazda's RX-Evolv. Mazda spokes-man Jim Bright said the company is weighing consumer demand.
Yuichiro Ito, general manager of corporate communications for Michelin Japan, says the company is working with Toyota, Honda and Mazda to develop cars with the Pax system. Other tire makers are deciding whether to sign up, says Michelin's Ahsbahs. The tire makers believe that in five years, more than 200,000 light vehicles a year could be fitted with the new tire in Europe and North America.
Although Pax has moved the industry toward a common standard and aroused automakers' interest, change is slow. That is because of the cautious nature of the industry, says analyst Ludwig. "The auto companies do not make major changes quickly, whether it's a new tire or a type of paint," Ludwig said. "They want to test and test and test to avoid a problem down the road."
Says Michelin's Ito: "The engineers are excited about the technology of these tires and want to plunge ahead. But the managers are conservative."
You can e-mail writer Edmund Chew at edmundchew@aol.com; Catherine Makino, Chris Wright and Dave Guilfordcontributed to this report
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