GMC 1993 Safari Owner's Manual page 283

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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 the tires are cold.
Overinflated tires are more likely to be cut, punctured, or broken
by sudden impact (as when you hit a pothole). Keep tires at the
recommended pressure.
Worn, old tires can cause accidents. If your tread is badly worn,
or if your tires have been damaged, replace them.
Don't drive over 85 mph (135 km/h) even if it's legal, unless you
have the correct high speed rated tires.
Underinflated tires pose the same danger as overloaded tires.
Inflation-Tire Pressure
The Certificationrrire label which is on the rear edge of the driver's door
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.
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