2014 Chevrolet Express 2500 Cargo Owner Manual - Page 313

Vehicle Care 10-63 When It Is Time for New Tires Factors such as maintenance, temperatures, driving speeds, vehicle loading, and road conditions affect the wear rate of the tires. Some commercial truck tires, including Goodyear LT225/75R16 G949 RSA and Goodyear LT225/ 75R16 G933 RSD, may not have treadwear indicators. If the tires do not have treadwear indicators, replace the tires when the tread depth is down to 3.2 mm (1/8 in) for the front tires, or 1.6 mm (1/16 in) for the rear tires. See Tire Inspection on page 10-61 and Tire Rotation on page 10-61 for additional information. The rubber in tires ages over time. This also applies to the spare tire, if the vehicle has one, even if it is never used. Multiple factors including temperatures, loading conditions, and inflation pressure maintenance affect how fast aging takes place. GM recommends that tires, including the spare if equipped, be replaced after six years, regardless of tread wear. The tire manufacturer date is the last four digits of the DOT Tire Identification Number (TIN) which is molded into one side of the tire sidewall. The first two digits represent the week (01-52) and the last two digits, the year. For example, the third week of the year 2010 would have a four-digit DOT date of 0310. Vehicle Storage Tires age when stored normally mounted on a parked vehicle. Park a vehicle that will be stored for at least a month in a cool, dry, clean area away from direct sunlight to slow aging. This area should be free of grease, gasoline or other substances that can deteriorate rubber. Parking for an extended period can cause flat spots on the tires that may result in vibrations while driving. When storing a vehicle for at least a month, remove the tires or raise the vehicle to reduce the weight from the tires. Treadwear indicators are one way to tell when it is time for new tires. Treadwear indicators appear when the tires have only 1.6 mm (1/16 in) or less of tread remaining.