When It's Time For New Tires - GMC 1999 Sierra 1500 Pickup Owner's Manual

Service & Appearance Cam
When It's Time for New Tires
K1656
One way to tell when it's time for new tires is to check the treadwear
indicators, which will appear when your tires have only 2/32 inch (1.6 mm) or
less of tread remaining.
You need a new tire if:
You can see the indicators at three places around the tire.
You can see 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 can't be repalred well
because of the size or location of the damage.
Dual Tire Operation
If
your vehicle has dual rear wheels, the outer tire will usually wear faster
than the inner tire. Your tires will wear more evenly and last longer if you
rotate the tires periodically. If you're going to be doing a lot of driving on
high-crown roads, you can reduce tire wear by adding 5 psi (35 kPa) to the
tire pressure in the outer tires. Be sure to return to the recommended
pressures when no longer driving under those conditions.
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