5 Things That Will Void Your CoverageTires are among the most important replacement parts that we purchase for our vehicles. We expect them to last for years — or at least as long as their advertised life. But tires occasionally wear out prematurely. Road debris causes flats. A spare tire is the short-term solution, of course. But then the tire has to be repaired or replaced, and it's good to know if there's a warranty in place to defray the costs.

Road hazards, tire defects and mechanical wear are some of the things that can cause a flat or premature wear. Most tires come with warranties that can protect consumers from having to pay full price on a new tire.

Tire Life
Most tiremakers have determined that the usable life of a tire is either six years from the date of purchase or when there's just 2/32nds of an inch of tread left. While there's no federal law regulating tire wear, Ron Margadonna, senior technical marketing manager for Michelin Tires, says that the 2/32nds measurement has been adopted by most states.

This measurement is difficult to visualize without a reference point, but there are at least two indicators that a tire is nearing the end of its life. Tires sold in North America are required to have tread-wear indicators, which are found in the tire tread's grooves. The wear indicators look like small bars of tread that run perpendicular to the groove. If the wear of the tire has reached these indicators, it's time for a new tire.

Another measure is the penny method. Put a penny in the groove of the tire, upside down and with Lincoln's head facing you. The distance from the top of Lincoln's head to the edge of the coin is about 2/32nds of an inch. So if the top of Lincoln's head is showing, you'll need to replace the tire. A similar method involves using Washington's head on a quarter to measure 4/32nds of an inch, but this is a safety indicator, not a way to support a claim that a tire has worn out prematurely.