Question of the Month: What vehicle tire strategies and technologies are available to save fuel?
Answer: It’s easy to understand why tires are essential to a vehicle, but tires also play an important role in your vehicle’s fuel economy. Tires affect resistance on the road and, therefore, how hard the engine needs to work to move the vehicle. By maintaining proper tire inflation or investing in low rolling resistance or super-single tires, you can improve your vehicle’s fuel economy. Whether you drive a light-duty vehicle (LDV) or heavy-duty vehicle (HDV), there is a tire strategy or technology to help you increase your miles per gallon (mpg).
Proper Tire Inflation
Properly inflated tires increase fuel economy, last longer, and are safer. Oak Ridge National Laboratory estimates that you can improve your gas mileage by up to 3.3% by keeping your tires inflated to the proper pressure. In fact, under-inflated tires can lower gas mileage by up to 0.3% for every one pound per square inch drop in pressure in all four tires. It is especially important to keep an eye on tire pressure in cold weather because when the air becomes cold, the tire pressure decreases.
You can find the proper tire pressure for your vehicle on a sticker located on the driver’s side doorjamb or in the owner’s manual. Also, check to see if your vehicle is equipped with a tire pressure monitoring system (TPMS), which will illuminate a dashboard light when the tire inflation, in one, multiple, or all tires reaches a certain pressure threshold. Fleet managers, in particular, may consider using telematics with a TPMS to assist their drivers with maintenance. Even if a vehicle has a TPMS, however, it is still good practice to manually check your vehicle’s tire pressure in order to ensure all of your tires are properly inflated.
Low Rolling Resistance Tires
Rolling resistance is the energy lost from drag and friction of a tire as it rolls over a surface. This phenomenon is complex, and nearly all operating conditions can affect how much energy is lost. For conventional and hybrid electric passenger vehicles, it is estimated that about 3%-11% of their fuel is used just to overcome tire rolling resistance, whereas all-electric passenger vehicles can use around 22%-25% of their fuel for this purpose. For heavy trucks, this fuel consumption can be around 15%-30%.
Installing low rolling resistance tires can improve vehicle fuel economy by about 3% for LDVs and more than 10% for HDVs. In LDVs, a 10% decrease in rolling resistance can increase fuel efficiency by 1%-2%. Investing in low rolling resistance tires makes economic sense, as the fuel savings from the use of these tires over the life of the vehicle can pay for the additional cost of the fuel-efficient tires. Most new passenger vehicles are equipped with low rolling resistance tires, but make sure you keep rolling resistance in mind when shopping for replacement tires.
Reducing vehicle drag can provide significant fuel economy improvements. One way HDVs can reduce drag is by replacing traditional dual tires with one super-single tire—also called a wide-base or single-wide. In Class-8 heavy-duty vehicles (see the April Question of the Month, http://www.eereblogs.energy.gov/cleancities/post/2016/04/20/vehicle_classifications.aspx, for a definition), this can save fuel by reducing vehicle weight and rolling resistance. A super-single tire is not as wide as two tires, so there is a slight aerodynamic benefit as well, further improving vehicle efficiency.
For more information, see the following pages:
- Alternative Fuels Data Center:
o Low Rolling Resistance Tires (http://www.afdc.energy.gov/conserve/fuel_economy_tires_light.html)
o Vehicle Maintenance to Conserve Fuel (http://www.afdc.energy.gov/conserve/vehicle_maintenance.html)
o Vehicle Parts and Equipment to Conserve Fuel (http://www.afdc.energy.gov/conserve/equipment.html)