Flat tire, by Flickr user Lissalou66Enlarge Photo
It wasn't always this way. In the past, using low rolling resistance tires meant that you'd get slightly higher mileage, at the expense of many more noise, limited tread wear, and greatly compromised traction and grip in the wet.
But Consumer Reports, in its new July issue now hitting newsstands, tested low-rolling-resistance tires and confirmed that they offer much better performance than they used to—with all-around ratings for three-season use as good as those for many general all-weather tires.
Rolling resistance, which is due mostly to the flexing of tire sidewalls and the gripping action of the tread, accounts for about four percent of fuel use in the city and about seven percent on the highway, according to the U.S. Department of Transportation.
What makes the new ones different? In the past, says CR's tire program leader, Gene Petersen, rolling resistance was cut—literally—by shaving weight off the tire and using a slightly different, tread design that was also much shallower. "Unfortunately, when you develop a tire along those lines, tread life and wet grip are compromised," he said.
Better compounds make it possible
Petersen says that in newer tires, much of the improvement is in the compound; adding silica to the compound, in place of carbon black, is a start.
In the latest tests, the Michelin Energy Saver A/S had the lowest rolling resistance of any all-season tire evaluated by CR in recent years, yet it also earned "good" ratings for snow traction and ice braking and performed well in hydroplaning resistance and emergency handling. And with as long of an estimated tread life as most all-season radials, it's truly a greener choice.
Petersen says that the Goodyear Assurance Fuel Max and Cooper GFE are also among those that should rack up fuel-cost savings without compromising performance. The Cooper GFE was a surprisingly good tire for winter grip as well.
Green tires no longer just for green cars
The other change is that 'green' low-rolling-resistance tires are being delivered for the replacement market; they aren't only offered in just a few sizes that are intended only for hybrid or diesel models. "We're seeing them sized for most family vehicles today," he said. Before, they'd only been designed for specific original-equipment applications, where they helped to achieve slightly higher EPA ratings while sacrificing performance in some way.