WASHINGTON (May 5, 2003)—Are wide-base single truck tires the future of the industry?
Michelin Americas Truck Tires (MATT) thinks that its X-One tire—the only wide-base single tire available commercially in the U.S.—can at least grab a significant portion of the market, thanks to its weight reduction, performance and fuel economy benefits.
Goodyear, however, is more circumspect, believing that the future of wide-base single tires rests largely on the issue of how many times the casings can be retreaded. Bridgestone/Firestone, meanwhile, is betting its Bridgestone Greatec wide-base single tire, already on the market in Europe, will make a splash in the U.S. when it's introduced here in the third quarter.
Also, Continental Tire North America Inc. is testing prototypes of a wide-base single tire it plans to introduce in the U.S. in 2005, based on research that has been going on at parent company Continental A.G. in Germany for some time.
Wide-base single tires, sometimes called “super singles”—though Michelin avoids the term as denoting an earlier, failed attempt at the technology—have obvious advantages over dual tires, according to tire makers. One is weight savings, and this is the factor that leads to all the other advantages.
“One tire replaces two,” said Al Cohn, Goodyear manager of strategic initiatives and communications. “It's not really double the size of a dual tire, so the weight is slightly less.” Because the weight is less, the truck gets better fuel economy, along with bigger payloads and improved performance and handling. “Drivers like the feel of a single tire,” he said.
In addition, a wide-base single tire allows for lower wheel costs—about $1,040 less on average, according to wheel manufacturer Alcoa Wheel Products.
However, some concerns remain regarding the tires, including the weight of the required wheel assembly.
“The wheel assembly for a wide-base single tire weighs 250 pounds, so it's hard to manipulate,” Mr. Cohn said. “You'd better have a big guy in your store as the technician to service it.”
Also, the “limp-home” capabilities of a dual-tire arrangement simply aren't available with single tires, he said. “With dual tires, you can still make it home if one of them blows. When a wide-base single tire blows, you're stranded.”
But the major question that lingers over wide-base singles, Mr. Cohn said, is that of retreadability.
“It's a huge issue,” he said. “In line-haul trucking, you have to get two retreads for the tire to make it economical. With a wide-base tire, you're likely to get one, but we don't know yet whether you can get two. A wide-base single isn't the same as two tires, but about 70 percent of two tires.
“Maintaining proper air pressure becomes absolutely crucial in this case, because you don't have the built-in safety factors that you do with dual tires,” Mr. Cohn added. “That's why we're still evaluating wide-base singles—if we can't get two retreads, we don't see a future for this baby.”
Goodyear is appraising its wide-base singles in its “focus fleets,” or test accounts, across the U.S., Mr. Cohn said. Michelin, however, is already on U.S. roads with its X-One, and Bridgestone will be shortly with the Greatec.
Michelin has a press packet touting the X-One's advantages and accomplishments, claiming the tires—which have specific models designated for drive and trailer positions—have helped truckers increase their payloads by nearly 15 percent while increasing fuel economy nearly 10 percent. Freightliner L.L.C. is offering X-Ones as original equipment on its Freightliner, Western Star and Sterling trucks, and has given MATT its “Masters of Quality” component suppliers' award for the eighth year in a row, the company said. Freightliner officials could not be reached for comment.
On the retreadability issue, a Michelin spokesman said X-One retreads are already in the field. “We can't really answer the question about whether the casings can be retreaded twice, since the tire has only been on the market since the fall of 2000,” the spokesman said. “The new tires in the field have such long tread lives that it's impossible to say whether they can be retreaded twice.”
One major concern about previous wide-base single tires involved the greater road damage they caused compared with dual tires. However, Michelin-funded research at the Virginia Tech Transportation Institute suggests that the X-One is no more damaging to road surfaces than dual tires (see related story on page 23).
Market acceptance for the X-One has been very good, the spokesman said, although he refused to talk about sales or market share.
Bridgestone's Greatec tires, meanwhile, have an ultra-low aspect ratio that allows them to replace dual tire configurations on trucks and buses, according to company publicity. Bridgestone makes the same claims for the Greatec that Michelin does for the X-One—including lower weight, increased fuel economy and increased load capacity. It also claims the Greatec is environmentally superior to dual tires by reducing the amount of scrap rubber and allows an increase in interior space available for seating.
In addition, Bridgestone offers a type of limited run-flat system for the Greatec, called “Aircept”—an amalgam of “assistant inner ring interceptor.”
Launched last year in Europe, Aircept is a type of rubber chamber or bladder that is fitted into the well of the rim and inflated to a pressure greater that that of the tire itself. A top layer of non-woven aramid fabric and the pressure inside the Greatec tire cavity keep the bladder in its prescribed stand-by size, Bridgestone said.
If the pressure drops in the tire, the Aircept chamber expands to fill the cavity, supporting the load and allowing the truck to keep going until the driver can get it to a servicing point. A monitor informs the driver of the pressure loss.
DaimlerChrysler A.G. is using Greatec tires with the Aircept technology as original equipment on certain models of its Actros line of Mercedes-Benz trucks in Europe. However, when Greatec tires have their U.S. debut this summer, they won't feature Aircept, according to Don Darden of Bridgestone/Firestone Commercial Marketing.
The truck market is essentially different in Europe than in the U.S., which makes the Aircept technology more pertinent there, he said.
“In Europe, there are single-axle tractors where stability is crucial,” he said. “If those tires lose air, it can be disastrous. Over here with the Greatec, if you have a loss of air, you will have some handling problems, but it's one of four tires that goes, not one of two as in Europe.”
Bridgestone also points out the lower aspect ratio of wide-base singles—in some cases down to 45-series—induce stresses that can lead to distortion of the bead and belt areas. To deal with this, Bridgestone developed a “waved” belt structure and a tip bead package, which wraps the ply cords completely around the bead.
Sales of wide-base single tires are not going to make a huge difference to the bottom lines of commercial tire dealers, Mr. Cohn said. “This is a niche market, not an enormous percentage of the market,” he said. “You still have the service and support for super singles, and a super single costs more than a single dual tire would.”
Also, the equipment dealers need to service wide-base singles is very little different from what they need to service dual tires, the firm's spokesmen said. “They need nothing more than a wider cage to put the tire in when they service it,” Mr. Darden said.
In February and March, Conti displayed prototypes of wide-base single tires at its Uvalde, Texas, testing grounds.
“We've been working with super singles in Germany, and while they're still in the testing phase, that's almost completed,” said Cara Junkins, product planning manager for Conti's Commercial Division. A Conti sister company is working on run-flat technology that could apply to the super singles, but that's still on the drawing board, according to Ms. Junkins.
“Considering where we're at, and also that no major issues have come up in field testing, we think 2005 is realistic for the introduction of a super single in the U.S.,” she said. “If for some reason a problem should crop up, we'll take the tire back into development. We're too far along in the process to drop it.”