Dual Tire Operation - GMC 2004 Sierra 1500 Pickup Owner's Manual

When to Check
Check your tires once a month or more.
Also, check the tire pressure of the spare tire.
How to Check
Use a good quality pocket-type gage to check tire
pressure. You can't tell if your tires are properly inflated
simply by looking at them. Radial tires may look
properly inflated even when they're underinflated. Check
the tire's inflation pressure when the tires are cold.
cold means your vehicle has been sitting for at least
three hours or driven no more than 1 mile (1.6 km).
Remove the valve cap from the tire valve stem. Press
the tire gage firmly onto the valve to get a pressure
measurement. If the cold tire inflation pressure matches
the recommended pressure on the tire and loading
information label, no further adjustment is necessary.
If the pressure is low, add air until you reach the
recommended amount.
If you overfill the tire, release air by pushing on the
metal stem in the center of the tire valve. Recheck the
tire pressure with the tire gage.
Be sure to put the valve caps back on the valve stems.
They help prevent leaks by keeping out dirt and
moisture.

Dual Tire Operation

When the vehicle is new, or whenever a wheel, wheel
bolt or wheel nut is replaced, check the wheel nut torque
after 100, 1,000 and 6,000 miles (160, 1 600 and
10 000 km) of driving. For proper torque and wheel nut
tightening information, see "Removing the Flat Tire
and Installing the Spare Tire" in the index.
The outer tire on a dual wheel setup generally wears
faster than the inner tire. Your tires will wear more
evenly and last longer if you rotate the tires periodically.
See "Tire Inspection and Rotation" earlier in this
section. Also see "Scheduled Maintenance Services" in
the Index for scheduled rotation intervals
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CAUTION:
If you operate your vehicle with a tire that is
badly underinflated, the tire can overheat. An
overheated tire can lose air suddenly or catch
fire. You or others could be injured. Be sure all
tires (including the spare) are properly inflated.
See "Tires" and "Inflation – Tire Pressure" in the Index
for more information on proper tire inflation.
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