Packed Snow Performance of Low Rolling Resistance Class 8 Heavy Truck Tires - Executive Summary

The National Research Council's (NRC) Surface Transportation (ST) portfolio, at the request of Transport Canada (TC), conducted a study of several brands of Class-8 long-haul low rolling resistance (LRR) tires, previously verified under the U.S. Environmental Protection Agency's (EPA) SmartWay program, to assess their performance in 'packed snow' winter conditions.

LRR tires, often characterized by unique materials, treads, dimensions and weights, are designed to reduce the amount of rolling resistance, and in turn, the amount of energy consumed as the tires roll along the road. In heavy-duty trucking applications, research and testing has shown that the installation of LRR tires on a tractor-trailer combination could result in a potential fuel savings of 4 to 11% [7] and offer corollary reductions in greenhouse gas emissions.

The United States Environmental Protection Agency (EPA) and the U.S. National Highway Traffic Safety Administration (NHTSA) recently finalized their Heavy-Duty National Program that established fuel economy and greenhouse gas emissions standards for medium-duty and heavy-duty engines and vehicles. Environment Canada published the proposed Heavy-duty Vehicle and Engine Greenhouse Gas Emission Regulations in the Canada Gazette, Part I on April 14, 2012.  The standards contained in these proposed Regulations align with the U.S. program, while also considering the specific characteristics of the Canadian fleet and related safety standards.

To comply with the proposed Canadian regulations, it is expected that truck manufacturers and importers will increase the penetration of fuel saving technologies, including LRR tires, to equip on vehicles for sale in Canada. While some manufacturers, importers and truck owner-operators already equip selected vehicles with LRR tires in Canada , some members within the Canadian trucking industry have expressed concerns that LRR tires may have reduced winter road traction performance compared to non- LRR tires, particularly in snow covered road conditions.

Because there was limited data available to assess this issue, TC asked the NRC to undertake a preliminary study of LRR tire traction for Class-8 long-haul vehicles, based on a cross-section of commercially available LRR tires in Canada.

To undertake this study, several laboratory tests were performed by Smithers-Rapra , on a selection of LRR and non- LRR SmartWay verified tires, specifically:

  • rolling resistance was measured using two different dynamometer-based test procedures, specifically SAE J1269 and ISO 28580;
  • durability was tested using the FMVSS 119 test procedures, and tested until failure;
  • snow traction was measured using a modified version of the ASTM F1805 test standard.

In addition to the laboratory tests, NRC also performed vehicle-based track testing at the General Motors Cold Weather Development Centre in Kapuskasing, Ontario.  Loaded trailer and unloaded trailer straight-line braking tests, and unloaded trailer turning tests were performed to compare the performance of a Class-8 tractor and a 53-foot van body semi-trailer with five different configurations of SmartWay verified LRR test tires and one configuration of non-SmartWay verified tires . Snow conditions were relatively consistent throughout the testing, with penetrometer measurements between medium pack and medium-hard pack snow as defined by ASTM F1805-06. Grooming was performed at the end of every test day.

Based on the testing performed, several key results emerged:

  • The lab testing demonstrated that, on average, tires marketed as low rolling resistance have 29% lower rolling resistance than their conventional counterparts;
  • All LRR and non- LRR tires passed the FMVSS minimum durability requirements . Additionally, when tested to failure, there was no discernible trend of performance bias towards LRR or non- LRR tires; and,
  • During laboratory (ASTM F1805 1) and vehicle-based track testing LRR tires demonstrated comparable levels of snow traction to non- LRR tires.

With the exception of the tires that are specifically marketed by their respective manufacturers as a high-traction tire, the results of this preliminary study indicates that the current generation of LRR tires can offer a similar level of snow traction performance as conventional tires, while reducing fuel consumption and emissions. Put in the context of Canadian trucking, there are many factors that must be considered when purchasing tires for a tractor and trailer combination. The advent of low rolling resistance tires has given owners and operators one more tire characteristic to consider.

The full report, Packed Snow Performance of Low Rolling Resistance Class 8 Heavy Truck Tires (PDF, 1.16MB), is available as a PDF.

1 Modified ASTM F1805 test procedure.
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