GMC Sierra Owners Manual
We recommend that the tires, including the spare tire, if the vehicle has one, be inspected for signs of wear or damage at least once a month.
Replace the tire if:
• The indicators at three or more places around the tire can be seen.
• There is cord or fabric showing through the tire's rubber.
• The tread or sidewall is cracked, cut, or snagged deep enough to show cord or fabric.
• The tire has a bump, bulge, or split.
• The tire has a puncture, cut, or other damage that cannot be repaired well because of the size or location of the damage.