INDIANAPOLIS, Ind. — With a proposed rulemaking for the second phase of the joint EPA/NHTSA greenhouse gas/fuel economy standards for heavy trucks expected this month, some manufacturers are concerned about what’s to come.

The new standards will take effect on post-2018 model year trucks and for the first time, will likely regulate trailers as well. They are a continuation of the Phase 1 GHG standards that covered model years 2014 to 2018 commercial vehicles.

While the first phase focused on using off-the-shelf technologies that were already widely used, the second part of the program is likely to promote the use of more technologically advanced components and systems.

Michael Hayn, senior field engineer, central region with Bridgestone Americas, said his company is concerned about how the new rules will impact tires. Specifically, as more aerodynamic fairings are added to trucks and trailers, he worries that tire maintenance will suffer because they’ll be less accessible for inflation pressure checks.

“We have concerns about how these aerodynamic technologies will impact tire inflation maintenance and accessibility for inspections,” he said. “The tighter the cavity is around the tire, the more of an issue it becomes.”

Hayn said there’s also some concerns that the more confined space within which the tire resides could cause heat generated by the braking system to accumulate.

“Will it increase brake heat in the tire area?” he asked. “Right now there is no hard and fast engineering formula for that. We’ll have to watch to ensure future technologies don’t have a negative impact on tire performance.”

While the burden of compliance with the new regulations will rest on the OEMs, Hayn said fleet managers must be aware of the tire replacement requirements on new vehicles. Hayn advised reading the fine print to determine if you’re required to replace low rolling resistance tires with tires that are equal to or better than the OE tires.

This may mean having conversations with your tire supplier to find out which products qualify as being equal to or better than the ones they replace. In other cases, Hayne said the operator will only be required to replace tires with low rolling resistance tires. In that case, the SmartWay list of verified tires is the industry’s only definitive list of low rolling resistance tires.

Another issue Hayn foresees is that the rules may continue to ignore the benefits of using retreads.

“Retreads are nearly half of all commercial tires sold last year,” he pointed out, adding retreads are not addressed in Phase 1 of the regulations and may not be included in Phase 2 either. “Some people when they purchase new vehicles will supply tires for that vehicle and if you supply retreads for that vehicle, there is no provision on what tires you can and can’t supply to that new vehicle purchase.”

Amy Kopin, compliance and regulatory affairs with Daimler Trucks North America, shared some concerns of her own. She said Daimler doesn’t want to see separate categories for the engine and vehicle, as was the case in Phase 1.

“We want just one standard,” she said. “Just tell us what the number is.”

Providing separate categories for engine and vehicle means integration isn’t fully rewarded, Kopin pointed out.

“As it stands, it doesn’t credit powertrain integration,” she said, noting Daimler should get credit for the improvements it can deliver by integrating its own engine with its DT12 automated manual transmission.

She also wants to see real-world data used to support the program.

“For the linehaul market, we’ve seen a divergence between engine test data improvements and the real-world,” she said. “Some engines that get better CO2 numbers on the dynamometer do worse in real-world fuel economy and that doesn’t help the regulatory integrity of this program. We don’t want to end up with fuel economy standards that don’t result in real-world improvements for our customers.”

Also, while the DOE-funded Supertruck program has been a worthwhile learning exercise for the manufacturers that participated in it, Kopin said she hopes the new standards don’t lean too heavily on the Supertruck concept.

“Supertruck is a great exercise for our engineers,” she said. “It gave us an opportunity to look at what does work and what doesn’t work for our customers, without consequences to our customers. We don’t believe it’s appropriate for the EPA to look at the Supertruck as a guide when they set the standards for Phase 2.”

The standards should reflect real-world conditions and not force technologies on the industry that don’t reduce total cost of ownership, Kopin argued.

“We don’t want to see complex, expensive technologies forced on the market, especially if it has a negative impact on vehicle weight or aerodynamic characteristics,” she cautioned. “We want our customers to be able to choose what they want, what works for them and what gives them the real-world benefits they expect.”

Brian Mormino, executive director, worldwide environmental strategy and compliance with Cummins, said the first phase of the standard was effective and hopes Phase 2 will be similarly executed, without major disruption to the industry.

“I think they got Phase 1 right, in terms of structure and other aspects, because frankly, most people didn’t even know we had a new rule in 2014,” he said. “That’s a pretty good sign.”