The EPA recently announced it has established a verification program for retread tires designed for use on line-haul trucks and trailers. Low rolling resistance retread tires verified by EPA’s SmartWay Partnership can be expected to deliver a fuel savings of at least 3% compared to common retread products currently in use. When these become available, they will be able to be used on SmartWay-certified tractors and trailers.
To appreciate why it’s a good idea to use low rolling resistance tires, it helps to understand how rolling resistance can cost fleets money. All tires are flexible and will deform as they roll down a highway. As they flex, they transform mechanical energy into heat energy, which is lost and can be substantial. Tire rolling resistance can account for up to one third of the fuel consumed by an over-the-road tractor-trailer combination.
Everything else being equal, the less flexing and deforming a tire undergoes as it rolls down the road, the lower its rolling resistance will be, and thus the more energy-efficient it will be. How a tire is constructed, of course, is important in determining its rolling resistance, and tire manufacturers have made great strides in developing many low rolling resistance tires that offer good fuel efficiency. Low rolling resistance tires are widely available for both familiar 18-wheel configurations and for 10-wheel applications with wide-base singles.
The influence of a tire’s original design on fuel economy will persist throughout the life of the casing, but it can quickly be negated if proper tire pressure is not maintained on a regular basis. It is easy to understand how a tire with low pressure will flex more than one that is properly inflated. Such flexing not only causes poor fuel economy, it also can destroy the tire itself, as all the “road alligators” on our highways bear witness.
Almost immediately after the EPA issued its protocol for retreads, Continental Tire the Americas announced it had submitted two retread tire products for verification as low rolling resistance technologies under the SmartWay Transport Partnership’s new performance standards. Continental’s HDL Eco Plus ContiTread drive axle tire and its HTL Eco Plus ContiTread trailer tire were officially submitted for verification the same day as the EPA announcement was made, according to Roger Stansbie, Continental’s director of radial truck tire technologies.
“Because of the adoption of these standards by the SmartWay Transport Partnership, the importance of manufacturing retreaded truck tires that perform just as well as new products has been brought to the forefront of fleet owners and professional drivers across the country,” said Paul Williams, executive vice president of Continental. “Our submission of these products for verification by SmartWay as soon as the standards were published is a testimonial to how committed Continental is to helping fleets lower their overall driving costs, over the entire life of their tires.”
The new test and performance protocol is applicable for both precured and mold-cured retreads intended for use in Class 8 tractor-trailer applications. It calls for utilizing a new standard-width Yokohama tire casing, but manufacturers can request using an alternate casing from an EPA verified single-wide new tire. The manufacturer is to make use of three new casings to build retreads using its normal manufacturing procedure and cure temperatures. The average of three test runs will be used to determine if the retreaded tire meets verification criteria.
Many tire tests are expected to be submitted by retread manufacturers to the SmartWay Partnership for product verification. This new opportunity will give operators one more chance to increase their fleets’ fuel economy and decrease their exhaust emissions.