The new MPG frontier

Tires and retreads on a roll to boost truck fuel efficiency

Government forces bent on reducing greenhouse gas (GHG) emissions from commercial trucks through increased fuel efficiency are driving manufacturers of truck tires and retreads to build products that deliver the largest possible contribution to miles-per-gallon performance. And if they don’t stay at the top of this game, tire and retread suppliers risk losing both OE-fitment and fleet-replacement market share.

That’s why tire and retread suppliers are all about closing what can be termed the mpg loop— the contribution rubber on the road makes to truck fuel efficiency, whether it’s as an original tire, a replacement tire, or as one or more retreads in fleet service.

Among the first developments to accelerate the birth of more fuel-efficient tires and retreads were the GHG limits placed on certain highway tractors, which were put forth by the California Air Resources Board (CARB) back in 2008 and came into effect in 2010.

CARB, by the way, estimates that by the close of 2020, its GHG reg will have saved truck operators “about $8.6 billion when diesel fuel consumption is reduced by as much as 750 million gals. in California and by 5 billion gals. across the nation.” And per CARB, that fuel-efficiency gain will come thanks to “improvements in tractor and trailer aerodynamics and the use of low rolling resistance tires.”

At pretty much the same time the CARB rule came about, mpg-savvy fleet owners as well as those responding to environmentally conscious shippers began to increasingly seek out tires that met the fuel-consumption criteria required for verification by the voluntary SmartWay program launched by the U.S Environmental Protection Agency (EPA).

Yet another mpg pressure point being applied to tires is the federal GHG rules that will begin to be imposed on commercial truck OEMs starting less than two years from now.

And to be sure, the contribution retreads can make to closing the mpg loop has at last caught the spotlight in a big way. In June, as part of its SmartWay program, EPA started a fuel-efficiency verification program for “tire retread technologies for use on linehaul Class 8 trucks.”

EPA states that the resulting verified “low rolling resistance retread products” will provide cuts in fuel consumption of at least 3% compared to the “most popular retreaded products now in use.”

Retread suppliers must test their products and demonstrate they meet the required performance criteria to be listed by SmartWay as verified retreads. EPA notes that to obtain the minimum fuel-consumption reductions, “verified tires or retreads must be used on the drive and trailer positions, with EPA-verified steer tires, and all tires must be properly inflated according to the manufacturer’s specifications."

“The additional expansion of the voluntary SmartWay program plus the CARB and GHG rules for OEMs together are pointing the industry in the right direction for improved fuel efficiency,” contends Guy Walenga, director of engineering- commercial products & technologies for Bridgestone Americas Tire Operations. “The goal, of course, is to reduce vehicle emissions for cleaner air and the side benefit is less fuel will get burned. It’s a win-win all around.”

FAST TRACK

Make no mistake, retread makers are making fast tracks to attain SmartWay verification. “We are in the testing phase of our fuel-saving products [for SmartWay verification] by one of the major EPA-approved U.S. testing labs,” relates Giampaolo Brioschi, product manager for retread supplier Marangoni.

“As soon as we have the results, we will apply for the SmartWay approval,” he continues. “In our case, we have combined Marangoni’s splice-less Ringtread technology with advanced compounding and tread designs to maximize fuel efficiency while maintaining very long mileage and increasing reliability.”

Continental Tire the Americas’ Commercial Vehicle Tire unit has already submitted two low rolling resistance retreads for SmartWay verification: the HDL Eco Plus ContiTread (drive-axle retread) and the HTL Eco Plus ContiTread (for trailers).

“Because of the adoption of these standards by the Smart- Way Transport Partnership, the importance of manufacturing retreaded truck tires that perform just as well as new products has been brought to the forefront,” says Paul Williams, Continental’s executive vice president for truck tires, the Americas.

“Our ContiTreads have always been made with the same standards and tread patterns as our new tires, which are the largest number of products verified by SmartWay today for low rolling resistance,” he notes.

Paul Crehan, Michelin’s product marketing director, reports that the company’s process to attain SmartWay verification of its retreads is “under way to apply for approval for a wide range of our products.”

“The SmartWay retread program is a real opportunity for the industry to close the loop on the mpg gains low rolling resistance tires and retreads deliver by ensuring fuel-efficient rubber is available throughout the product lifecycle,” says Bridgestone’s Walenga.

“Up until now,” he continues, “there’s not been a lot of emphasis on closing that loop in trucking, but having these targets out there will lead more fleets to consider retreads as a means of benefitting from fuel efficiency continuously.”

Walenga says having the “EPA imprint” on retreads will get the attention of fleet owners who had “previously tended to give up on fuel efficiency once a tire was retreaded. In short, we’re very glad EPA has done this.”

While Double Coin doesn’t yet supply retreads, Aaron Murphy, vice president of CMA, the North American subsidiary of Double Coin Holdings, is quick to point out that “once we enter into that segment of the business, which is in our strategic plan, we plan to provide verified-technology retreads that will be SmartWay-approved.”

Roger Stansbie, Continental’s director of radial truck tire technologies-the Americas, reports that the impact of upcoming GHG rules on tires for truck OEMs will be “slightly kinder” than what SmartWay verification requires of new tires in terms of rolling-resistance levels.

Regarding the GHG limits, Stansbie says that Continental is “already doing lots of testing with the OEMs and working on a new generation of tires” with the GHG rules in mind. “And the GHG specifics only suggest what the contribution of tires may be. But there’s the strong possibility that in the next five to 10 years, a 10 to 15% improvement in tire rolling resistance will be seen,” he predicts. “Keep in mind a 5% decrease in rolling resistance equals a 1% gain in fuel efficiency.”

Stansbie adds that such a performance mark as 10 or 15% better “has not yet been stated by SmartWay, but it has been suggested.”

Stansbie points out that, in general, the bigger challenge ahead for tire and retread makers is not what SmartWay, which is oriented toward long-haul trucking, or the federal GHG reg may require, but what must be done to reduce the rolling resistance of on/ off-road tires.

FINE-TUNING

He says the upshot of the GHG impact is that OEMs “may ask us to fine-tune rolling resistance further” to improve the mpg performance of more truck types. “And because the rule kicks in for 2014 truck models, the OEMs will begin production next year and the tires will have to be ready for them,” Stansbie notes.

“Yokohama has developed and produced fuel-efficient tires for years—from even before EPA and SmartWay became involved,” states Rick Phillips, Yokohama’s director of commercial sales. “This is something we continue to focus on. Every new commercial-tire product that we have on the drawing board has an eye on fuel efficiency, not only for our OEM partners, but also for our fleet partners who are dedicated to improving fuel efficiency.”

John Hagan, senior director of sales for Toyo Tire U.S.A., points to its M157 free-rolling axle tire for non-drive positions as a good example of an mpg-oriented tire that also combats irregular wear. He says the M157 is SmartWay-verified and features Toyo’s proprietary e-balance technology to provide a “uniform and consistent tire that delivers improved fuel economy while fighting irregular wear.”

He adds that the M157 also deploys a four steel-belt package to ensure uniform growth of the tread area. “This design reduces rolling resistance while also helping to reduce irregular wear; the result is an improvement in fuel mileage.”

According to Tim Miller, Goodyear’s customer marketing manager-Commercial Tire Systems, other examples of mpg-oriented tires are within Goodyear’s Fuel Max line, including these models: G316 LHT, G572 LHD, G662 RSA, G305AT LHD, G392 SSD, and G394 SST. “Goodyear’s Fuel Max Technology incorporates cool-running compounds and construction to help reduce truck fuel consumption,” he remarks. “Goodyear also offers retreaded tires with Fuel Max Technology.”

“Tires today are much more fuel-efficient than they were just a few years ago and as technology evolves, this will improve even further,” contends Yokohama’s Phillips. “Currently, tires actually play a relatively small role in fuel efficiency when compared to the engine and aerodynamics. But as vehicle manufacturers continue to improve on those factors, tires will play a larger role. So the engineering will continue to be a work in progress.”

TRADE-OFFS?

As to whether fleet owners should be concerned that the harder push now on for tire/retread mpg gains might lead to tradeoffs in durability and retreadability, Double Coin’s Murphy says there’s no doubt that’s a consideration when any manufacturer modifies its products.

“The durability/retreadability can’t suffer due to these mpg/GHG requirements or the overall tire costs to a fleet will increase,” he continues. “The key for us is to optimize all aspects of the tire’s functionality and performance so that the lifecycle costs of a Double Coin tire continue to be attractive to the end user.”

Yokohama’s Phillips points out that “typically, fuel-efficient tires run cooler than non-fuel-efficient tires so the cooler operating temperature actually helps prevent casing fatigue. This in turn helps the retreadability and durability of the tire.

“However,” he continues, “there are certainly other trade-offs for fuel efficiency. Fortunately, engineers have several ways to lower the rolling resistance in a tire. So depending on how the product is designed and manufactured, you may notice a little less mileage or a little less resistance to cuts and snags. The challenge is to utilize all the tire’s components in a way that deliver the expected fuel efficiency without compromising the total performance of the tire and its intended application.”

Continental’s Stansbie recommends that tire buyers continue to “pay close attention to what tire makers offer to ensure expected tread life and retreadability within the parameters for low rolling resistance.”

Phillips says Yokohama’s approach to the mpg/lifecycle trade-off is to “combine different elements of the tread, the rubber compound, the casing, and also the manufacturing process to deliver fuel efficiency as well as other performance standards.

“A common way to lower rolling resistance is simply to shallow the tread design,” he adds. “However, we were able to design and produce the 703ZL drive tire at 32/32 [tread depth] with low enough rolling resistance to be verified by EPA as a fuel-efficient product. It’s currently the deepest tread depth on the EPA list of verified products.”

POSITIVE UPSHOT

Double Coin’s Murphy says the GHG rules being imposed on truck OEMs are creating further impetus for lowering the rolling resistance of tires. “Double Coin is not only now providing EPA SmartWay-verified tires for those users that participate in the program, but we’re also reviewing all tires in our lineup for rolling resistance. Our goal is to lower these values on core products such that we can assist OEMs to meet the new [GHG] guidelines.

“Some products we supply already meet the [GHG] guidelines, and we’re continuing to work on others to reduce the rolling resistance,” he adds. “It’s an ongoing process that utilizes technology in tread patterns, casing components, rubber compounds, and a myriad of technical developments.”

Michelin’s Crehan says that to meet the specifics of the federal GHG category for heavy-duty trucks, there are six approaches OEMs can access to meet the targets. These are aerodynamics, weight reduction, extended idle shutdown (such as via APUs), speed limiting, and drive- and steer-axle tires with low rolling resistance.

“Selecting from these choices, the OEMs can make various adjustments to meet the heavy-duty GHG goals,” he explains. “For vocational trucks, though, only the steer and drive tires will matter, as those vehicles are not running fast nor do they have persons sleeping in them.”

Crehan notes that Michelin’s “general position” on both the SmartWay program and the CARB and GHG rules is positive. “Environmental sustainability and fuel efficiency are the targets and that is being well communicated to the trucking marketplace.”

Bridgestone’s Walenga reports that the tire maker has been working with truck OEMs it supplies for the past three to four months to get them the tire data they will need for their GHG calculations.

“The way it’s working is that if an OEM expects to use a particular tire on a certain truck, they need average rolling resistance quotients from us,” he explains. “And they need that data for each and every tire model they will buy. As it happens, our line of tires that are SmartWay-verified will handle most of the expected truck applications under the GHG rules.”

Along with his contention that the advent of SmartWayverified retreads will help close the mpg loop, Walenga says the positive upshot of the GHG rule will be “more fleets ending up with more fuel-efficient tires on their new trucks. From there, more fuel-efficient tires will get out into the marketplace. And fleets will be wise to buy replacement tires and/or retreads that are fuel-efficient to keep the mpg gains going for them.”

Double Coin’s Murphy points out that the truck tire market extends beyond tires that must meet specific mpg/GHG requirements. “Each fleet has its own criteria for operating,” he contends. “Standards like SmartWay or CARB may dictate to certain users which products to utilize. While it’s an important product, especially for linehaul fleets and those that participate in programs like SmartWay, Double Coin still produces and sells more tires that aren’t on the verified technology list at this time.

“In the replacement market,” he continues, “there are many applications where the need for verified technology is not mandatory due to applications or other requirements. I will say that both power unit and trailer OEMs are focusing heavily on the SmartWay-verified technology products at this time. Fleets and other end users seem to be turning towards products that can help their bottom line and lower costs.”

NO COMPROMISE

Yokohama’s Phillips says that fuel-efficient tires have “absolutely” become a de facto standard spec at many fleets. He says the truck’s application helps determine the need for fuel efficiency, “but for most linehaul and many regional operations, fuel efficiency plays a major role.”

“There’s always a risk involved when buyers feel forced to do something,” Michelin’s Crehan observes of the impact of the CARB and GHG rules on fleets. “But to be sure, a balanced approach is being taken by tire makers.”

He says it’s Michelin’s view that “no compromise in tire performance is required to meet the new rules” and that fleet owners should have “no inherent concerns around performance” about the tires they will be getting.

“That being said,” Crehan cautions, “it will still be important for fleets to work with their OEMs to spec trucks— including their tires—correctly for the best performance in their given application. Plenty of fleets already approach fuel-efficient tires as de facto specs,” he advises. Yet others do not view them that way.

“Per CARB, fleets operating in California will need SmartWay-verified tires and others will need them if required by certain [green-conscious] customers and, of course, new trucks starting in 2014 will come with low- GHG tires,” notes Crehan.

“To be sure, the awareness of the effect tires have on fuel consumption is becoming more clear,” he adds. “Still, right now, there are many fleet managers who can ‘see’ their tread wear—but not the impact tires have on their fuel costs.”

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