A Great Idea Deflated
Sydney Morning Herald
Friday February 24, 1995
THUMPETA, thumpeta, thumpeta ... The familiar, sickening sound of a flat tyre. It promises skinned knuckles, run pantyhose, intemperate language. At best, a long wait for road service. You'd think somebody would invent tyres that won't go flat.
Well, they did: more than 100 years ago. And they've been reinventing them ever since.
Mary Anne Backscheider of Junction City, Kansas, is one who drives them. "I love 'em," she said. "I really feel comfortable knowing I have them." Backscheider, a budget analyst at a United States Army hospital, is one of about 2,000 Chevrolet Corvette owners whose cars are shod with Goodyear Eagle GS-C extended mobility tyres, known in the trade as "run-flats".
Earlier this year, Backscheider put off a tyre repair for weeks, adding air when the Corvette's electronic sensor told her to. She couldn't feel a difference in ride or handling.
"I finally took it in to have it checked. They took it off and there was a screw in it," Backscheider said. The Kansas City Star featured her tyre repair in a story: she may have been the first motorist to have an official "flat" on the Goodyears.
Pneumatic tyres - those with air inside - were invented in the mid-1800s and the idea of preventing flats has been around almost from the start. A Goodyear history says J. B. McCune patented a tyre in 1891 that had several air chambers to keep it from going flat.
But until recently, run-flats required too many compromises to make them practical for the masses. A major drawback to the run-flat tyres used on presidential limousines, off-road racers and other specialty vehicles is that they generally can be used only once in the run-flat mode.
"For the general mass market ... if you use it once and have to throw it away and buy a whole new tyre, that's a disadvantage," said Mike Wischhusen, the product engineering manager at Michelin North America, the US arm of the French tyre-maker.
The specialty application run-flats have rigid inserts or plastic foam inside the tyre to give support when the air doesn't.
The Goodyears on Backscheider's Corvette and the run-flat tyres that Michelin says will become an option on a luxury performance sedan in the coming year have different construction. They rely on rigid sidewalls, not inserts, to maintain the tyre shape. And they can be repaired after they're used.
Goodyear says the tyres it puts on the Corvettes can go 300 km at 90 km/h with zero air pressure and still be repairable.
"This (type of tyre) is something we developed back in the early '80s," said Goodyear Tyre and Rubber's product design chief, Bill Egan. We demonstrated them to a couple of the (manufacturers) but they weren't ready. We kept pitching it at them, and they finally stepped up to the table." CAR manufacturers are reluctant to add complexity and cost to new cars and trucks for features customers aren't demanding, and run-flat tyres aren't yet on motorists' lists of must-have options. The tyre-makers say it may be years before consumers want them and are willing to pay extra for them.
There are other considerations besides demand: * Ride. A tyre with a sidewall thick enough and stiff enough for it to keep its shape, stay on the wheel and start, stop and manoeuvre safely can make a boulevard feel like a battlefield. That isn't so much a problem with highperformance cars such as a Corvette, which already have a stiff ride. Other types of cars would have to be designed with special suspensions that compensate for the ride qualities of run-flat tyres.
* Sensors. If the tyre doesn't go flat, how do you know it's picked up a nail? Backscheider's Corvette has electronic sensors in each wheel that detect low air pressure. It's an option offered with or without the run-flats, but it's required to make them practical and safe, manufacturers say.
* Cost. Tyre-makers expect run-flats to be about 20 per cent more expensive than conventional premium tyres. Add to that the cost of the sensor system. On a 1995 Corvette, the sensor system option is $US325 ($A424). To upgrade to the Goodyear run-flats from the standard highperformance tyres on Corvette costs $US70 ($A91.30).
* Service. Run-flats would have to be usable on conventional wheels and repairable by the same service people. "In order for this technology to be successful in the mass market, we can't be requiring service stations to invest thousands of dollars in new equipment," Michelin's Wischhusen said.
Down the road, run-flats have the potential to let carmakers eliminate spares from the standard equipment in new vehicles, but tyre makers aren't ready to predict that that will happen. They say motorists like the feeling of security they get from a spare in the boot, even if they never touch it.
Car makers don't like to tip their hands to competitors by talking about plans for future features on new cars and trucks. But it seems likely run-flats will turn up on other vehicles in the next few years.
PETER McKAY reports that the run-flat technology is yet to hit the spot with Australian motorists.
Kris Matich, the national marketing manager for Goodyear here, said the Australian operation doesn't stock the run-flat tyres and "we don't have any plans to import them. Goodyear hasn't had any demand locally for these tyres, which are now only available to fit sports models such as the Corvette, which isn't sold in Australia." But Matich believes the run-flats could have a serious future in an off-road application. "This seems like a more relevant market because it's inherently more inconvenient to get a flat out in the bush." He also points out that it makes better marketing sense. "The 4WD market is far bigger than the sports car sector occupied by the Corvette."
© 1995 Sydney Morning Herald
