Fuel efficient tires are designed to roll with less resistance, which in turn puts less strain on the engine. Original equipment tires are generally more efficient than about 60 percent of the replacement tires on the market today. When you switch from the original tires to the replacements, chances are you are losing gas mileage unless you take care to purchase tires with better rolling resistance. Some states are pushing for legislation that could better inform tire buyers as to the nature of their potential new tire purchases. Are those tires in the "60 percent less" crowd, or are they actual, bona fide fuel efficient tires? New labeling requirements for tires could change just how informed the public is when it comes time to replace those original tires.