2009 Jeep Grand Cherokee Owner's Manual - Page 343

STARTING AND OPERATING 341 Many states have laws requiring tire replacement at this point. Life Of Tire The service life of a tire is dependent upon various factors including but not limited to: • Driving style • Tire pressure • Distance driven 5 WARNING! 1 - Worn Tire 2 - New Tire These indicators are molded into the bottom of the tread grooves. They will appear as bands when the tread depth becomes 1/16 in (2 mm). When the indicators appear in two or more adjacent grooves, the tire should be replaced. Tires and the spare tire should be replaced after six years, regardless of the remaining tread. Failure to follow this warning can result in sudden tire failure. You could lose control and have an accident resulting in serious injury or death.