GMC 1993 Suburban Owner's Manual page 315

Poorly maintained and improperly used tires are dangerous.
Overloading your tires can cause overheating as a result of too
much friction. You could have an air-out and a serious accident.
See "Loading Your Vehicle" in the Index.
The resulting accident could cause serious injury. Check all tires
frequently to maintain the recommended pressure. Tire pressure
should be checked when your tires are cold.
Overinflated tires are more likely to be cut, punctured, or broken
by sudden impact, such as when you hit a pothole. Keep tires
at the recommended pressure.
e
Worn, old tires can cause accidents. If your tread is badly worn,
or i f your tires have been damaged, replace them.
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Even if it's legal, don't drive over 85 mph (135 km/h) i f you
have 16 inch tires.
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Underinflated tires pose the same danger as overloaded tires.
See "Special Tire Inflation" in this section for more information on
loading and inflation pressures at speeds above 65 mph (105 kmlh).
hfatkm-Tire Pressure
The Certificationnire 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 a mile.
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.
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