Long-haul tire spec’ing is evolving
The endless highway remains endless, but the cost of fuel, environmental laws, tire technology and the economy have changed. This new order has redefined long-haul tire spec’ing.
“There have been big changes in the industry,” says John Overing, PLNA segment manager, heavy truck, with Michelin Tire. He observes that trade with Asia has increased, with more goods heading inland by rail from ports before trucks distribute them. “We are seeing more hub and spoke, a change from purely long-haul to quasi-long-haul/regional applications in Canada.
“If you are only looking at the tire mileage records and not at how the fleet operation has changed, a tire manager could overlook a change in application from, for example, purely long-haul to more regional driving,” Overing suggests.
While the Michelin XZA3 is fine for purely long-haul driving, a fleet finding itself logging more regional kilometres might want to switch to an XZE regional tire. “It is a little more scrub-resistant, which reduces wear. The long-haul tire, if used for regional travel, will wear more quickly,” Overing says.
With their crowned roads and curves, regional highways put more stress on steering tires. Accelerated wear on shoulder areas and chipping and tearing are indicative of a change to more regional roads, as is a decrease in tire life. If you are a Bridgestone man and your regional kilometres are creeping upward, you might consider switching from the R287, more suited for line-haul applications, to the R280. This more multi-purpose tire is a good compromise between long-haul and local usage, according to Brian Rennie, director of engineering for Bridgestone Canada.
As the battle heats up to reduce greenhouse gases, so evolves the regulatory environment. For example, in 2004, the US Environmental Protection Agency launched SmartWay, which “identifies products and services that reduce transportation-related emissions,” including a recommended list of fuel-efficient tires and aerodynamic products for trucks. This January, California became the first state to make SmartWay law for trucks.
Tire managers with trucks heading for the Golden State should arm themselves with copies of the SmartWay tire list and the relevant California Environmental Protection Agency law. In short, as of Jan. 1, all 2011 trucks with 53-ft. trailers or longer have to be spec’d with tires on the SmartWay list. Older trucks will be captured by additional kick-in dates such as July 1, Jan. 1, 2012 and Jan. 1, 2013.
Oregon will soon adopt SmartWay as law. Other states will likely follow. In time, it will probably become impossible to do a long- haul trip in the US without passing through a state with such laws, according to Overing.
Fuel-efficient tire talk is the rage and SmartWay helps narrow the choices. To be on its list, a tire has to give “an estimated fuel savings of 3% or greater, relative to the ‘best selling’ new tires for line-haul trucks, when used on all five axles on long-haul Class 8 trucks.” As of mid-January, the list included close to 50 steer, drive and trailer tire types by eight tire manufacturers, including wide-base tires, also known as super singles.
These magnificent tires, one of which replaces a dual pair, are typically hailed as fuel savers. Controlled track tests have yielded savings nearing 10%, although Michelin promotes fuel savings from its wide-base tires in the 4% range. In a recent test with a fleet in western Canada, it compared its XDN2 dual and X One DN2 wide-base tire. Aside from the dual/wide-base difference, the two tires are otherwise identical in tread depth, similar in tread design and have a similar rubber compound. The X One DN2 delivered 4% better fuel economy.
According to Overing, wide-base tires help tire managers wriggle out of the corner in which the California Air Resources Board (CARB) regulations have painted them: how to select a low-rolling resistance tire that also delivers the traction necessary for Canadian operations. “With the new-generation designs, we have been able to reduce rolling resistance and maintain all other aspects of the tire’s performance; for example, traction and removal mileage. The X One DN2 is the only tire on the SmartWay list that is designed for winter traction, but which also meets CARB regulations.”
Rennie has a different take on the benefits of wide-base tires, which Bridgestone sells for drive and trailer positions under its Greatec model name. “If fuel savings is your only consideration, wide-base is not the optimum choice. We have fuel-saving duals that are equal to or better than the wide-base. Casing durability, and therefore retreadability, is still better on dual tires. Wide-base is not the be- all and end-all for SmartWay applications to save fuel.”
Greatec tires are more suitable for reducing weight, Rennie counsels: “If you can replace the weight, saved by the lighter wide-base tires and aluminum wheels, with revenue-earning payload, go wide, but fuel savings can be done with duals. Duals have less tread wear and less inconvenience [more availability] if a tire fails. If you are grossing out with weight, you can save weight with wide-base, but this is not an advantage in Canada outside of Ontario and Quebec.”
Rennie cautions against racing after fuel savings if driving fast is a value-added part of a fleet’s business. “A fuel-efficient tire’s advantages are decreased by about half by the overriding air resistance at higher speeds.” Still, trucks running fuel-efficient tires at 120 km/h still burn less fuel than trucks without them.
Mississauga-based Larry Hardy is the national manager of commercial sales for OK Tire Stores. He observes that the weight of the loads a fleet hauls and the application are important considerations when spec’ing tires, and that this is a fairly complex point of discussion. “We ask clients what they will be hauling. For example, 80,000 lbs. or a heavier haul like 120,000 lbs. GVW. Are they operating 100% loaded or running empty half the time? There could be 20 to 30 applications for what they are pulling. For example, a B-train might call for a high tread-depth tire that won’t wear out that quickly on multi- axle trailers that squirm. A dry van will want a shallower tread, [possibly a] fuel-efficient tire tri-axle application tire. A lowboy will want something different again.”
Rennie adds: “You could [be running] a close-spaced tandem trailer and use an R195 with an 11/32 tread depth, giving the advantage of low- rolling resistance and less irregular wear. But with a multi-axle with more spread and frequent turning at each end of a long-haul, there would be a requirement for a deeper tire and better resistance to side load scrubbing. The R195 would not be appropriate. I recommend the R196 with a 16/32 depth and a solid shoulder.”
He also notes that new regu
lations and equipment necessary to meet EnviroTruck, SmartWay and CARB requirements are pushing the loads on the front steer axle of a typical long-haul tractor closer to and beyond those recommended for standard tire size load limits at the maximum recommended speed of 120 km/h. Consequently, tire selection requires ever more care. “Exceeding the maximum speed rating under full load can impose not only faster and more irregular wear, but also internal structural damage to a tire. Bridgestone now offers higher ply ratings on the four main steer tire sizes,” Rennie counsels.
There are new tire families to consider. For example, Yokohama introduced its Zen Environment family of tires about a year ago. Increased toughness, lower-rolling resistance and better control of casing shape after long service are some of this family’s features, according to Greg Cressman, director of technical services with Yokohama. “The tires are oriented to ultimate fuel efficiency and increased retreadability.”
Those who spec’ tires with a view to retreadability and cost per kilometre should take note of Yokohama’s performance guarantees: “Our Zen tires have a seven-year warranty, during which we will cover casings used on paved surfaces for as many retreads as can be put on them; our normal warranty is four years and one retread. We have also affixed a higher casing value to this tire: a $125 credit. Our other tires have lesser amounts,” Cressman explains.
Since May, Cressman adds, “We also guarantee on-the-road performance with the Zen tire line. Based on the cost per kilometre, we guarantee that our Zen tires will cost 15% less per kilometre than the last tire on your truck. If not, we will pay the difference.”
Setting and maintaining appropriate tire pressure is critical for making sure the tires you have spec’d perform well. Tire managers will eventually have to consider tires with pressure monitoring technologies built into them. “The Tire Pressure Monitoring System (TPMS) is not that far away,” Hardy says. “I’m talking only a year or two out. You will be able to buy a tire (or rim assembly) with a TPMS chip or some sort of monitoring system.”
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