Tire manufacturers, not the government, test tires and assign their own grades. According to the Federal Trade Commission, treader grades are for comparison purposes only and are not intended to be converted into anticipated or promised tire mileage. Several polymers are used in a tire, depending on their performance characteristics. Even premium tires can show signs of premature or uneven treader and imprecise steering when vehicles have defective alignment or suspension parts. Correct vehicle alignment is a must and should be checked periodically.
Improper alignment causes excessive tire wear as well as increases fuel consumption.
Regular tire rotation about every 6,000 to 8,000 miles promotes more uniform wear for all tires on a vehicle. A tire engineered for low rolling resistance would provide horrible fuel economy when it is run under inflated. Running tires 20 percent under inflated by 6 to 7 pounds per square inch wastes fuel usage by as much as 10 percent. That amounts to Americans wasting nearly 4 million gallons of gasoline daily. Tire care is crucial in saving money at the pump.