Consumer Reports

Low-rolling resistance tires prove good value

By Consumer Reports
Consumer Reports’ recent tests of a new generation of fuel-efficient tires found that they not only save gas but are also good all-around performers. Two models it looked at — the Michelin Energy Saver A/S and the Cooper GFE — have low rolling resistance, a quality that can help a car get more miles per gallon.
Rolling resistance, or the force a tire needs to keep it moving down the road, accounts for about 4 percent of a vehicle’s fuel use in city driving and about 7 percent on the highway, according to the Department of Transportation. Replacing high-rolling-resistance tires can result in more than $100 in annual fuel savings.
Automakers often specify fuel-saving tires as original equipment to help a vehicle’s fuel economy numbers. But replacement tires aren’t limited to an automaker’s requirements, and attributes such as all-season grip and tread life are big selling points. In the past, consumers had to weigh a trade-off between low rolling resistance and other performance properties. In recent years, tire manufacturers have been achieving a better balance of rolling resistance and all-weather grip. And now they’re marketing tires specifically for their claimed fuel efficiency.
In CR’s tests of the Michelin Energy Saver A/S and Cooper GFE, the new formulations seem to be working. Both new tire models fared well, and the Michelin was exceptional. It not only had the lowest rolling resistance of any all-season tire CR has tested but also scored Very Good in dry and wet braking. It ranks second among all T-rated all-season tires.
The Cooper finished midpack in the group. Its rolling resistance was not as low as the Michelin’s, but it performed well in all-weather grip, hydroplaning resistance, and emergency handling.
By comparison, the Goodyear Assurance Fuel Max, the model that had the lowest rolling resistance in CR’s November 2009 test, rated somewhat lower among the highly competitive performance H-rated tires, though it performed well in most respects and displayed decent all-weather grip.
For comparison purposes, CR examined how the two newly-tested tires stacked up against 23 other models of T-rated tires it previously rated. In that ratings chart, the Michelin Energy Saver A/S ranked second overall behind the Michelin HydroEdge. The Cooper GFE ranked 11th overall.
CR’s overall score for tires emphasizes safety-related tests including braking, handling, and resistance to hydroplaning. CR also evaluates rolling resistance, ride comfort, noise, snow traction, ice braking and tread life.
Making a well-rounded choice
Don’t discount safety advantages or other performance attributes for the sake of fuel savings when selecting a set of tires. CR recommends you choose tires based on your driving style and the road conditions you commonly encounter. Use rolling resistance as a tie-braker.
Fuel savings from those tires might be appealing, but proper inflation pressure can have a bigger impact on fuel economy, no matter what tires you’re rolling on.
Efficiency labels for tires
The National Highway Traffic Safety Administration, or NHTSA, and California are trying to make tire fuel-economy ratings available to consumers. NHTSA has proposed a label that would assign a rating for fuel efficiency, wet traction, and tread wear based on a 100-point scale. California is considering options including a ratings system that would give the top 15 percent a fuel-efficiency rating.
But NHTSA hasn’t determined a method to present consumer information and will issue a rule at a later date. California is waiting for the federal government to take the lead.
CR notes that consumers should be aware that rolling-resistance scores, as proposed, apply to new tires. And if they are not inflated and maintained properly, their fuel-economy benefit disappears.