2013 Chevrolet Express 1500 Cargo Owner Manual - Page 308

10-60 Vehicle Care the front tires, or 1.6 mm (1/16 in) for the rear tires. See Tire Inspection on page 10‑58 and Tire Rotation on page 10‑58 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. Tire Inspection on page 11‑3 and Tire Rotation on page 10‑58. Also see Maintenance Schedule on page 11‑3. { WARNING If the vehicle is operated with a tire that is underinflated, the tire can overheat. An overheated tire can lose air suddenly or catch fire. You or others could be injured. Properly inflate all tires, including the spare. See Tires on page 10‑44 and Tire Pressure on page 10‑53 for more information on proper tire inflation. 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. 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 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.