GMC 1996 Sierra Owner's Manual page 299

Inflation
--
Tire Pressure
The Certification/Tire label. which is on the rear edge of
the driver's door, or on the incomplete vehicle document
in the cab, shows the correct inflation pressures for your
tires when they're cold. "Cold" means your vehicle has
been sitting for at least three hours or driven no more
than I mile ( I .6 km).
You can operate some vehicles at reduced inflation
pressures only when you'll be carrying reduced loads.
On those vehicles, the minimum cold inflation pressures
for a typical reduced load are printed on the Improved
Ride Tire Pressure label located on the driver's door.
Weigh the vehicle to find the load on each tire and see
the label for the minimum cold inflation pressures for
that load.
1
NOTICE:
~.
1
Don't let anyone tell you that underinflation or
overinflation is all right. It's not. If your tires
don't have enough air (underinflation), you can
get the following:
NOTICE: (Continued)
NOTICE: (Continued)
Too much flexing
Too much heat
Tire overloading
Bad wear
Bad handling
Bad fuel economy.
if your tires have too much air (overinflation),
you can get the following:
Unusual wear
Bad handling
Rough ride
Needless damage from road hazards.
When to Check
Check your tires once a month o r more.
Also,
check
the
tire pressure of the spare tire,
6-49