Pontiac 1993 Sunbird Owner's Manual page 177

Service & Appearance Care
Inflation-Tire Pressure
The Tire-Loading Information label
which is on the rear edge of the driver's
door shows the correct inflation
pressures for your tires, when they're
cbld. Cold means your vehicle has been
sitting for at least three hours or driven
no more than a mile.
NOTICE:
Ddn't let anyone tell you that
underinflation
or overinnation is all
dght. It's not. 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.
If your tires have too much
i
,
(overinflation), you can get:
Unusual wear
Bad handling
Rough ride
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.