Chevrolet 1994 Astro Passenger Owner's Manual page 266

Inflation
-
Tire Pressure
The Certificatioflire 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.
NOTICE:
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:
0
Too much flexing
Too much heat
Tire overloading
0
Bad
wear
0
Bad handling
0
Bad fuel economy.
If your tires have too much air (overinflation),
you can get:
@
Unusual wear
0
Bad handling
6
Rough ride
6
Needless damage from road hazards.
When to Check
Check your tires once a month or more.
Don't forget your compact spare tire. It should be at
60 psi (420 kPa).
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.