Fleet Maintenance - 18

What's up with

LOW ROLLING
RESISTANCE TIRES?
When it comes to reducing vehicle
emissions, tires play a key role.
By Erica Schueller

hen it comes to reducing heavy duty truck
greenhouse gas (GHG) emissions and
improving fuel efficiency, tires play a key
role. Specifically, fleets may consider specifying low rolling resistance (LRR) tires in
order to lower emissions and fuel consumption.

Rolling resistance 101

Rolling resistance is the friction or drag created
between the tire interacting with the road while
the vehicle is in motion. Tires with lower rolling
resistance, often denoted as LLR, create less drag.
"The lower the rolling resistance, the less fuel
consumed," says Pat Meisenholder, product technical manager for tire maker Michelin North
America. "It is estimated that a third of heavy
duty truck fuel consumption is used to overcome
rolling resistance."
There are a number of factors that categorize
tires as low rolling resistance. Tire manufacturers are working to create next-generation tire
compounds to assist with extending the wear and
retreadability of tires.
"The tire's rolling resistance can be changed
many different ways including changes to the
rubber compounding, tire shape, tread pattern,
tire construction, and weight," explains Phil
Mosier, manager of commercial tire develop-

»»This cutaway of a
tire shows the layers
of the Michelin Dual
Energy Compound tread.
The green area signifies
a fuel-efficient top tread
layer which optimizes wear resistance and
traction. The blue area represents a coolrunning tread rubber bottom layer that reduces
casing temperature for low rolling resistance.
Image courtesy of Michelin North America

less tread equates to less drag, it also means the
tire would likely need to be replaced more often.
"For many tire manufacturers, that has meant
lowering the starting tread depth to get better
fuel economy," Mosier says. "While that solves
one problem, it creates another - fewer miles to
removal and less traction."
Sanjay Nayakwadi, director of product strategy, U.S. and Canada, Bridgestone Americas Tire
Operations, advises tire manufacturers must
address these needs for fleets in order to deliver a
product that both meets the federal emissions and
fuel efficiency requirements while also providing
longevity and durability.
"[Tire] manufacturers will need to not only design
tires that meet verification requirements but also
tires that fleets will be happy with as they watch

"It is estimated that a third of heavy
duty truck fuel consumption is used
to overcome rolling resistance."
Pat Meisenholder, product technical manager, Michelin North America

ment for Cooper Tire. "The key to developing a
successful product is coming up with the right
combination of all these factors to get what the
consumer needs."
When it comes to tire tread, in particular, LRR
tires often have a lower average tread depth. While

18 Fleet Maintenance | February 2020

their bottom line and expect more out of their investment," Nayakwadi says. "As tire manufacturers work
to achieve the right combination of durability and
efficiency, it's important for fleets to consider tread
wear needs, traction requirements, and the application of their tires from a holistic point of view."

SmartWay verification

Launched in 2004, the U.S. EPA's SmartWay
program certifies products that assist with saving
fuel and reducing emissions. This includes, but is
not limited to, tires.
When it comes to SmartWay verification criteria,
Bridgestone's Nayakwadi notes the program considers tire size, tread depth, performance, and testing
requirements. "All SmartWay-verified tires offer low
rolling resistance," he adds. "However, just because a
tire claims to be low rolling resistance doesn't mean
it's SmartWay-verified, unless it's been through the
official testing and verification process."
As it relates to tire SmartWay certification, a tire
must reduce GHG emissions and fuel consumption
by 3 percent or more, compared to the best-selling
tires available on the market for similar applications.
Fleets looking to specify new tires, or to confirm
whether current tire specifications meet these
requirements, can visit the SmartWay website.

Application matters

Long haul and regional haul fleets look to benefit
most from specifying an LRR tire. "The applications that run at consistent steady-state speeds
gain the most benefits from fuel-efficient tires,"
Cooper's Mosier notes. Specifying LRR tires for
urban applications such as pick-up and delivery,
refuse collection, or jobsite applications, or any
operation with extended idling times and slower
speeds would not yield the same fuel economy
improvements. Changes to drivetrain technology and aftertreatment systems would be required
instead to address these concerns.
"A long-haul application will clearly see the
benefits of a rolling resistance tire in a much
shorter time span than a vocational application,"
Michelin's Meisenholder says.
As far as location on the vehicle, the U.S. EPA
greenhouse gas model notes steer tires account

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