Chevrolet SUBURBAN 1993 Owner's Manual page 315

Don't let anyone tell you that underinflation or overinflation is all right. It'-
9 .
If your tires don't have enough air (underinflation) you can get
Too much flexing
Too
much heat
tire overloading
Bad wear
Bad handling
Bad fuel economy.
I
If your tires have too much air (overinflation), you can get:
Unusual wear
Bad handling
Rough ride
Needless damage from road hazards.
nth 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.
Simply looking at the tires will not tell you the pressure, especially if you
have radial tires-which may look properly inflated even if they're
underinflated.
If your tires have valve caps, be sure to put them back on. They help
prevent leaks by keeping out dirt and moisture.
Special Tire Inflation
If you have 16 inch tires on your vehicle, and:
-
You'll be driving for very long at speeds of 66 mph (105 km/h) to 75
mph (120 km/h) where legal, inflate tires 10 psi (70 kPa) more than
the recommended cold inflation pressure,
-
You'll be driving for
very
long at speeds of 76 mph
(120
kmih) to 85
mph
(135
km/h) where legal, cold inflation pressure should be
increased by
10
psi (70 kPa) and you must also reduce axle load
capacity by
10%.
Do not drive over 85 mph (135 kmlh) even if
it's legal.
-
Inflation pressures should never exceed
10
psi (70 kPa) above the
inflation specified for the maximum load of the tire.
6-50