Factors such as maintenance, temperatures, driving speeds, vehicle loading, and road conditions affect the wear rate of the tires.

Treadwear indicators are one way to tell when it is time for new tires.
Treadwear indicators appear when the tires have only 1.6mm (1/16 in) or less of tread remaining.
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.
Tire Rotation
Buying New TiresAutomatic Transmission
It is better not to park with the engine running.
If the vehicle is left with the engine running, follow the proper steps to be
sure the vehicle will not move.
If parking on a hill and pulling a trailer.
The automatic transmission has a shift lever located on the console between the
seats.
...
Child Restraint Systems
Rear-Facing Infant Seat
A rear-facing infant seat provides restraint with the seating surface against
the back of the infant.
The harness system holds the infant in place and, in a crash, acts to keep the
infant positioned in the restraint.
Forward-Facing Child Seat
A forward-facing chil ...
Headlamp Aiming Procedure
Open the hood.
Measure from the floor to the center of the headlamp bulb. Some
headlamps have an aim dot marked on the headlamp lens.
At the screen, measure from the floor and place the horizontal tape at
the measured distance.
Measure from the reference line on the floor to the le ...