ORNL: Single Wide-Base Truck Tires Improve Fuel Economy

30 June 2006

Replacing the standard two thinner tires per wheel with a single wide-base tire improves the fuel efficiency of heavy-duty tractor-trailer trucks and allows them to be made to run with more stability, according to studies by Oak Ridge National Laboratory (ORNL).

Interstate tests by ORNL’s National Transportation Research Center show gas mileage increased nearly 3% with use of wider single tires on tractor-trailers. Bill Knee, who headed the study, said the change also allows widening of the trailer frame by six inches, providing a much more stable configuration.

We noticed that there was about a 2.9% fuel saving in using the new generation single wide tires over the standard dual tires. These trucks do 125,000 miles per year on the average. They currently get five miles per gallon. You can see there is a considerable amount of savings dollar-wise that can be realized through tires like this.

—Bill Knee

With those figures, a 3% improvement in fuel economy would reduce fuel consumption by about 728 gallons per year per truck.

The wide base tires improve fuel efficiency by decreasing weight and rolling resistance. Knee said tire formulation and the design of the tire are likely contributors to the fuel savings.

The fuel economy tests were conducted along a route from Western Michigan to Portland, Ore., that involved many types of terrain, varying weather conditions and different levels of congestion.

A 2005 study by the EPA on single wide truck tires and aerodynamic devices singly and in combination on Class 8 vehicles using a test track found improvements in fuel economy ranging from 3 to 18%—and, surprisingly, NO_x reductions ranging from 9 to 45%.

ORNL will conduct additional testing of five instrumented trucks over a 12-month period beginning this fall. Lessons learned from these types of studies are preliminary to further efforts to develop a heavy truck of the future that will be more energy-efficient and stable than conventional trucks. The research is funded by DOE’s Office of FreedomCar and Vehicle Technologies.

Resources:

• ORNL Heavy Vehicle Safety Research Center (HVSRC)

• EPA: Effect of Single Wide Tires and Trailer Aerodynamics on Fuel Economy and NOx Emissions of Class 8 Line-Haul Tractor-Trailers

• Single Wide-Base Tires (SmartWay)

• Wheels and Tires