Low Rolling Resistance Tires
Rolling resistance is the energy lost from drag and friction of a tire rolling over a surface. The phenomenon is complex, and nearly all operating conditions can affect the final outcome. It is estimated that 3%–11% of light-duty fuel consumption for conventional and hybrid electric vehicles is used to overcome rolling resistance. Because all-electric passenger vehicles are extremely efficient in energy use, they can use approximately 23% of their energy for this purpose. For heavy trucks, this quantity can be as high as 15%–30%. Installing low rolling resistance tires can improve fuel economy by about 3% for light-duty vehicles (LDVs) and more than 10% for heavy-duty vehicles (HDVs). In LDVs, a 10% decrease in rolling resistance can increase fuel economy by 1%–2%.
New vs. Replacement Tires
New cars are generally equipped with low rolling resistance tires that offer better fuel economy. This helps the auto manufacturer meet their Corporate Average Fuel Economy (CAFE) standards. However, no requirements are currently placed on replacement tires. Therefore, if you want to purchase fuel-efficient replacement tires, you must research to figure out which tires have low rolling resistance.
Signed into law on December 4, 2015, the Fixing America’s Surface Transportation (FAST) Act requires the U.S. Department of Transportation, U.S. Environmental Protection Agency (EPA), and U.S. Department of Energy to develop regulations for passenger vehicle tire fuel efficiency standards by December 2017. Some exemptions apply. For more information, refer to H.R. 22, Section 24331.
Proper tire inflation plays an important role in fuel efficiency. By keeping your tires properly inflated, you can improve your gas mileage by up to 3%. Under-inflated tires can lower gas mileage by 0.2% for every one pound per square inch (psi) drop in pressure in all four tires. To find the proper tire pressure for your vehicle, check the sticker on the driver’s side door or the owner’s manual.
According to a North American Council for Freight Efficiency report, the use of low rolling resistance tires, in either a dual or a super-single configuration, is cost effective over the life of the vehicle. In essence, this means the fuel savings pays for the additional cost of the low rolling resistance tires. This report estimates that the opportunity for cost-effective energy savings from low rolling resistance tires is substantial—for a Class 8 truck, “the purchase price of a tire is approximately $0.04 per mile, but given the range in rolling resistance among dual tires, tires could account for $0.14 per mile to $0.28 per mile in fuel costs.” Advancements in tire thread life and traction will reduce the frequency of low rolling resistance tire replacement.
Relevant Information and Reports
California Energy Commission - Tire Efficiency Proceeding Documents
California Energy Commission - California State Fuel-Efficient Tire Report
Fuel Economy.Gov - Hybrid and Other Advanced Technologies
1015 Driving Cycle
A Japanese emissions test cycle characterized by slow speed urban driving.
Highway Federal Emissions Test (HWFET)
Highway federal emissions test (the "highway" cycle for the EPA city/highway test procedure). This is a very gentle high-speed cycle.
LA92 Drive Cycle
1992 test data from Los Angeles that consists of city/highway mix and can be characterized by aggressive urban driving.
New European Drive Cycle (NEDC)
The New European Drive Cycle (NEDC) is a European Union test cycle characterized by a city/highway driving mix.
SC03 Drive Cycle
This is supplemental drive cycle number 3 for the federal test procedure. It consists of a city/highway mix of driving.
Urban Dynamometer Driving Schedule (UDDS)
The urban dynamometer driving schedule is characterized by gentle urban driving.
US06 is defined as a duty cycle with aggressive highway driving.