Tires that keep rolling for miles after being punctured might seem like something every consumer would want.
But many drivers who have purchased vehicles with these newfangled tires -- known as run-flats in the industry -- say that while they do run after losing air pressure, they come with a list of problems. Replacements are expensive and can be hard to find. Durability can be poor.
For some drivers, these ills outweigh the convenience of not having to stop at the side of the road, jack up the car and change to a spare tire.
The tires have become available on a wider range of vehicles in the past two years but haven't caught on quite as quickly as manufacturers expected. Though they used to appear mostly on expensive sports cars like the Chevrolet Corvette, they are now available on more basic passenger cars. BMW made them standard equipment on the latest version of its entry-level 3-Series cars, which went on sale two years ago. Toyota Motor and Honda Motor mount them on some of their minivans.
For consumers who have long viewed tires as a cheap, long-lasting commodity, the spread of run-flats has led to frustration and sticker shock at replacement time. The minivan driver who has become accustomed to spending $70 to $80 per tire can be surprised to find that each replacement run-flat on his new van costs $200. In addition, he may have to replace two tires at once to maintain proper tread-wear balance -- a lesser problem with many conventional tires.
Run-flats -- whose makers include Bridgestone, Goodyear Tire & Rubber and Pirelli -- are constructed differently from conventional tires and have a thicker, reinforced sidewall that is stiff enough to support a vehicle's weight after losing air pressure. They allow you to continue driving for roughly 50 to 100 miles after damage that would leave typical tires flat and unusable. Pressure-monitoring systems alert the driver when the tire loses air.
Automakers pitch run-flats as a safety feature because they let drivers avoid stopping on busy highways and other dangerous locations. They also say they like the design flexibility they get by eliminating the space-consuming spare tire. Even though run-flats are heavier, the lack of a spare tire can save vehicle weight overall, helping fuel efficiency.
On the downside, the tires force people to find specific replacement models, often from a dealership selling their make and model of car. Critics say that even if there is a dealer within the tires' run-flat range, your particular tire may not be in stock. That may not matter if a motorist gets a flat on a late-night trip home from work or on the way to an important meeting -- the types of scenarios tire makers often cite. But the prospect is more daunting in the middle of a lengthy road trip, especially when tire shops and car dealers may be closed.
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When John McTavish's 2006 BMW 3-Series sedan got a flat during a two-day, 600-mile trip, he was 30 miles from his Bonita Springs, Fla., home. So he and his wife returned home and took a different car.
"It seems to me the lack of a spare with these tires is a major disability if you take a trip on a weekend or holiday, or if you are caught without tire pressure more than 100 miles from a dealer," McTavish says.
Mike Filipek, an engineer with Bridgestone/Firestone, says that run-flats have roughly the same speed and distance limitations as the compact "doughnut" spares found in most vehicles. In a pinch, one can also replace a run-flat tire with a conventional one long enough to complete a trip. He also says the company began working on run-flat tires only after drivers repeatedly said in surveys and studies that they wanted them.
"Consumers truly want the smallest amount of hassle in their lives, and run-flat tires move in that direction," says Filipek.
Still, unlike other safety equipment such as side air bags, anti-lock brakes and electronic stability control, run-flat tires have yet to gain the broad acceptance that tire makers had expected. Indeed, more than a decade after they began to appear on a handful of sports cars, run-flats are available on relatively few vehicles and account for only about 1% of the tire market.
Their price has helped hold back run-flat tires. Tire makers say they can cost as much as 30% more than comparable conventional tires. But those comparable tires are higher-performance conventional tires that typical buyers wouldn't consider. In the real world, run-flats can easily cost double what consumers are accustomed to paying.
Harmon Fischer, a retired supermarket executive in Jefferson, La., and BMW Mini Cooper driver, calls run-flats "possibly the biggest rip-off," in part because they can't be repaired like conventional tires -- or at least many shops refuse to patch them because they lack the necessary certification required by the tire makers.
Developed in part for the unique hazards of off-road rally competition and military use, run-flat tires began turning up on a handful of exclusive passenger cars, including the exotic Porsche 959 in the late 1980s and Chevrolet Corvette and Plymouth Prowler in the mid-1990s. They have since been used on Lexus, Mercedes-Benz and BMW cars and on certain Toyota and Honda minivans. Most run-flats are really high-performance tires and as such have higher prices and shorter tread life than typical mass-market tires.
The newest models increasingly have been designed for family-oriented vehicles like large and midsize sedans and crossovers. Such tires will have longer tread life and lower prices than earlier run-flat designs. Still, Bridgestone's Filipek doesn't expect consumers' historically slow adoption rate of the technology to speed up appreciably.
"I remember how long it took people to switch to radial tires from the older bias-ply tires, so I fully expect run-flats to catch on slowly."
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A recent study by J.D. Power & Associates placed run-flat tires on a list with stability control, night-vision systems, blind-spot detection and side-impact air bags as features that consumers find most attractive before knowing the estimated market price. The tires were the second-most highly rated feature among consumers before they knew the cost. But their high price hurt consumer interest. After the cost was revealed, run-flats fell to seventh on the list, behind stability control, backup assist and premium sound systems.
This article was reported and written by Jonathan Welsh for The Wall Street Journal.
Published Aug. 17, 2007
