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Imagine a tire design that can deliver improved stability, comfort, fuel economy and leave room for more payload. Leading tire manufacturers such as Michelin, Bridgestone/Firestone, and Continental ar...

Imagine a tire design that can deliver improved stability, comfort, fuel economy and leave room for more payload. Leading tire manufacturers such as Michelin, Bridgestone/Firestone, and Continental are touting all these advantages in trying to sell fleet managers on a new generation of wide base tires gradually entering the Canadian market.

Fuel savings are due to reduced rolling resistance, according to the manufacturers, primarily because there are only half as many tire sidewalls to absorb and waste energy. “In Europe they have been working with single tires for several years and a large volume of trucks are running on single tires. They learned that single tires tend to be more fuel efficient; e.g., through lowering rolling resistance,” explains Ralph Beaveridge, Michelin’s marketing director for truck tires.

Michelin began selling its new wide base tire, the 445/50R22.5, in Canada in January 2001. Sold under the X-One family name, there are four tire types: the X-One XTA, a long-haul trailer tire; the X-One XTE, a regional applications trailer tire; the X-One XDA, a long-haul drive tire with an emphasis on fuel efficiency and long wear and the X-One XDA-HT, a long-haul drive tire for high-torque applications where traction is a concern.

“We know from years of testing that when you lower rolling resistance by three percent, you increase fuel economy by one percent. By switching from our most fuel-efficient drive tire, the XDA2, to our X-One XDA, and the trailer from the XT-1 to the X-One XTA, fuel efficiency would increase by approximately five percent.

“If we compare ourselves to other [less energy-efficient regular tires], the savings become even [greater] … I can tell you that with one fleet, changing both the tractor and trailer tires resulted in fuel savings of over 10 percent.”

Bridgestone/Firestone Canada also reports fuel savings in the two to five percent range. Manufactured under the Greatec product name, Bridgestone/Firestone is evaluating a 445/ 50R22.5 size wide base tire, designed for the drive and trailer position, for North America.

A smaller version of the American Greatec was launched in Japan in 1997 and in fall 2001 for European buses. Bridgestone/Firestone has been showing the Greatec at truck shows in North America, but, says Brian Rennie, the manufacturer’s director of engineering, “It is still in the evaluation stage.” The company plans to make a limited quantity of the tire available in Canada in the second half of this year.

Dan Freight, in Joliette, Que., is road-testing wide base tires for Michelin and Bridgestone/ Firestone. “So far, we have had a good response from the drivers, who like the handling and performance,” says Rennie, whose company is collecting wear data and driver comments on stability, handling, traction and unusual performance conditions.

These new-generation tires are significantly different from the 65 series wide base tires from which they evolved. Typically seen on cement trucks, the 65 series are taller. Michelin’s 445/50 R22.5 is the wide base equivalent to the low-profile 22.5″ tire, which, says Beaveridge, is the most common tire size in North America. The 455/55 R22.5 is the wide base equivalent to the 11R22.5, which is the most popular truck tire in Canada. “They are both designed to maintain the same height of vehicle as the equivalent tire type,” Beaveridge explains.

The manufacturers report that wide base tires can actually make a rig more stable than a dual. Switching to wide base tires moves the vehicle track outboard by about two inches, according to Beaveridge. Raised centre of gravity is simply not an issue, he says. “Practical experience shows that stability is enhanced.”

Trailer manufacturers will be able to take advantage of the slightly narrower wide base tire, versus a dual setup, to increase trailer stability. For example, a tanker with tapered sides could be lowered a few inches into the liberated space between the wheels, lowering the centre of gravity and increasing stability.

Trailer manufacturers will also be able to build more trailer volume in that extra space to increase carrying capacity. “We’re talking about 200-250 pounds per axle of weight savings by converting from duals to wide base tires. This is a saving of about 1000 pounds on a regular tandem trailer,” says Beaveridge.

Driver comfort is reportedly enhanced as well. One U.S. fleet driver running Michelin tires on a cross-country trip, according to Beaveridge, reported, “‘I’ve never driven anything so comfortable and stable in my life.'” Braking distance is supposed to be less as well, according to Beaveridge.

Bridgestone/Firestone is also counting on lower purchasing and operating costs to sell the tires. “There will be a saving over purchasing two regular tires,” says Peter Krafchick, marketing manager, commercial truck. Rennie adds, “The other big saving is on hardware and maintenance. There are half as many wheels. Also, there is the saving in time it takes to mount and dismount the tires.”

Continental Tire North America is testing a drive and trailer tire in North America as well, but has yet to settle on a product name. “Continental already has a 495/55R22.5 wide base tire that has been established in Europe. By working with our parent company [Continental AG] and using their information and knowledge, we believe we will be able to bring it in next year,” says Cara Junkins, the company’s commercial products planning manager. Continental expects to see all of the advantages presented by the other manufacturers.

The most difficult legacy of the old 65 series tires that manufacturers have to overcome is the restrictive legislation provincial departments of transportation imposed on wide base tires in the 1990s. “Old studies showed that the old-technology tires caused two to seven times as much road damage as the regular duals,” says Beaveridge.

Existing regulations limit the per-axle load when running wide base tires to 9000 kilograms in Ontario, 8000 kilograms in Quebec and just 6000 kilograms per axle in the rest of the country. For interprovincial carriers , the penalty makes running wide base tires uneconomical.

The new generation tires have a bigger contact area than 65 series wide base tires. The Greatec, for example, has about 87 percent of the contact area that the 75 series tires have. New belt construction and tire pressure also reduce the impact of the new generation tires on the road.

Research done at the Virginia Polytechnic Institute and State University, “essentially shows that there is no significant road damage caused by wide base tires compared to duals. I like to refer to the wide base tire as damage neutral,” says Beaveridge. The results of the study were presented and published at the Transportation Research Board in Washington, DC in January 2002.

These results were also presented to the Council of Deputy Ministers Task Force on Vehicle Weights and Dimensions last November in Montreal. “The process is in play,” says John Pearson, the Task Force’s secretary. “Michelin was able to provide the results of its research and they have been taken back to the respective DoTs. Their engineering divisions are studying the results. The Task Force was open to seeing the results of the research of the design.

“The Task Force members have committed to completing their review and discussing this in the next few weeks. They may come back with questions, accept the study results that Michelin gave them or review the results and see nothing new.”

If the research Michelin presented to the Task Force is persuasive, Pearson believes that changes to the National Memorandum of Understanding and to provincial regulations could be made with little delay.

The Rubber Association of Canada is also working to broaden understanding of the new wide base tires. “We have been working with the Canadian Council of Motor Transport Administrators to build awareness at the provincial level so we can get to the point where we can have wide base tires from coast to coast. Concerning the impact on the roads, they are quite a conservative lot
,” says Glen Maidment, the association’s president. “They are in charge of taking care of the roads … they are reluctant to make changes that could jeopardize the service life of the roads.

“The key issue is counteracting the claim that there is an impact on the pavement. I think that the real nut of the issue is that the load limits provinces have are antiquated. It is not that tires are an issue, it is that regulations have not been updated to reflect reality.”

Another issue which concerns Pearson is that of changing regulations for the benefit of the new-generation tires, but which still exclude the old 65 series. As well, he says, “Michelin and others cannot speak to the general applicability of their tests … to other wide base tires.” Additionally, each manufacturer will have to defend its own tires.

Michelin, meanwhile, will be presenting the Task Force with a draft of how the regulations could be reworded. “I believe it is our responsibility to step beyond showing the good news and make some suggestions on how the regulations could be reworded so that the new-generation tires can be run unhindered, but so the old-generation tires will continue to be run under the lower weight limits,” says Beaveridge.

“Without exception, everyone I spoke to seemed receptive to the idea, but I think it is our responsibility to provide them with a roadmap for how they could modify the regulations. Any proposal we make has to be enforceable by DoT inspectors,” says Beaveridge. He believes that a certification process and an identifying logo on approved tires could work; in the long run, Pearson thinks that performance-based regulations may be the solution.

“It is the legal restriction that is limiting [the tire’s] viability at this point, which we need to overcome,” says Rennie.

Beaveridge adds, “In Quebec there are several fleets that are interested in these tires. They have let the DoTs know that they want to run these tires without penalty. It is not a baby step when you can talk about 10 percent fuel savings or a reduction in vehicle weight of 1000 pounds. The sooner we can allow the industry to take advantage of these savings, the better.”

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