Chevrolet 2007 Silverado 1500 Pickup Owner's Manual page 551

How to Check
Use a good quality pocket-type gage to check tire
pressure. You cannot 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
inflation 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.
High Speed Operation (SS Silverado)
CAUTION:
{
Driving at high speeds, 100 mph (160 km/h)
or higher, puts an additional strain on tires.
Sustained high-speed driving causes
excessive heat build up and can cause
sudden tire failure. You could have a crash
and you or others could be killed. Some
high-speed rated tires require inflation
pressure adjustment for high speed
operation. When speed limits and road
conditions are such that a vehicle can be
driven at high speeds, make sure the tires
are rated for high speed operation,
in excellent condition, and set to the
correct cold tire inflation pressure for
the vehicle load.
If your vehicle has P275/55R20 size tires and you
will be driving at high speeds, speeds of 100 mph
(160 km/h) or higher, set the cold inflation pressure
to the maximum inflation pressure shown on the tire
sidewall, or 38 psi (265 kPa), whichever is lower.
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