• | 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. |