| • | A tire performance criteria
(TPC) specification number is molded in the sidewall near the tire size of
all original equipment tires. |
| • | The TPC specification number ensures that the tire meets GM's
performance standards for the following conditions: |
| • | A specific TPC number is usually assigned to each tire size. |
| • | The following characteristics on replacement tires should be the
same as on the original tires: |
| • | Replace the original tires with tires of the same TPC specification
number. |
| • | Use of any other tire size or type may affect the following conditions: |
| - | Speedometer/odometer calibration |
| - | Vehicle ground clearance |
| - | Tire clearance to body and chassis |
| • | Install new tires in pairs on the same axle. |
| • | If it is necessary to replace only one tire, the tire should be
paired with the tire having the most tread in order to equalize the braking
traction. |
Replace the tires under the following conditions:
| • | Tires are worn to a point where 1.6 mm (1.16 in)
or less tread remains, or the cord fabric shows. |
| | To help detect this condition, tires have built-in tread wear indicators
that appear between the tread grooves when the tread is worn to 1.6 mm
(1/16 in) or less. |
| | Replace the tire when the indicators appear in two or more adjacent
grooves at three spots around the tire. |
| • | The tread or sidewall is damaged in one of the following
ways: |
| | The tread or sidewall is cracked or either cut or snagged deeply enough
to expose the cord or the fabric. |
| - | The tread or sidewall is cracked. |
| - | The tread or sidewall is cut deeply enough in order to expose
the cord or the fabric. |
| - | The tread or sidewall is snagged deeply enough in order to expose
the cord or the fabric. |
| • | One of the following conditions exists in the tire: |
| - | Slight sidewall indentations are normal and should not affect the ride. |
| • | One of the following conditions exists in the tire: |
| - | Other damage that cannot be correctly repaired because of the
size or location of the damage. |