PARIS -- Michelin expects run-flat tire sales to surge as car manufacturers start to fit them on higher-volume cars.
So far, run-flat tires have been mostly confined to premium or luxury models, such as Audi's A6 and A8, BMW's Mini Cooper or the Rolls-Royce Phantom.
But BMW's decision to make them standard on its new 1 series is a breakthrough in volume, says Michelin, which is one of the tire suppliers for the new entry-premium model.
Nissan and Honda also plan to use Michelin's PAX run-flat tires but the Japanese carmarkers have not yet specified on which cars.
"Run-flat tires sales are finally taking off," said Michelin spokeswoman Fabienne de Brebisson.
Michelin expects PAX sales to grow to between 200,000 and 250,000 four-tire units a year by 2005.
In 2000, Michelin, Goodyear and Pirelli agreed to exchange run-flat technology and offer automakers multi-supplier deals to reduce their business risk. Bridgestone also manufactures run-flat systems.
Run-flat tires allow a motorist to drive a car with a punctured tire up to 200km at a maximum speed of 80kph before repairing the tire.
Bridgestone is the main supplier of run-flat tires for the BMW 1 series, but Michelin also supplies BMW with its zero-pressure (ZP) tires for the model. The 1 series goes on sale in September. BMW has capacity to build 150,000 1 series a year.
The PAX system consists essentially of a rubber ring around the rim of the wheel inside the body of the tire. If the tire loses air pressure, the rubber ring supports the tire tread so the car can still operate at lower speeds. ZP tires have reinforced sides to withstand the increased flexing of running when deflated.
BMW has been the industry leader in adopting run-flat technology. It first used it on the limited-edition Z8 premium roadster, which went on sale in the US in 2000 and was discontinued last year.
A car with run-flat tires can be designed with more trunk capacity because the spare wheel, jack and tools are eliminated. But the weight saving is reduced because run-flats weigh more than standard tires.
Initially, four PAX tires weighed the same as five standard tires, so there was no net gain. But four PAX tires now weigh the same as 4.7 regular tires.
"We keep working on that weight issue," said a Michelin spokesman.
But French automakers say PAX tires require a stronger chassis and suspension, which adds to manufacturing costs.
Tires are also so-called unsprung weight -- mass that directly reacts with road irregularities without being softened by the suspension -- so PAX tires make it more difficult to provide a smooth ride.
Renault sold a few thousand first-generation Scenics with the PAX system, but doesn't intend to do so with the new Scenic. "The value for money isn't there," a Renault spokesman said.
Peugeot product planning chief Bruno de Guibert said the upcoming 1007 small car, which is aimed at the same buyers as the 1 series, won't use run-flat tires.
"It's not a question of cost, it's a question of weight and comfort," he said. "The technology needs fine tuning."