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Manufacturers of passenger vehicles and light trucks determine
this number based on the vehicle’s design load limit, that is, the
greatest amount of weight a vehicle can safely carry and the
vehicle’s tire size. The proper tire pressure for your vehicle is
referred to as the “recommended cold inflation pressure.” (As
you will read below, it is difficult to obtain the recommended tire
pressure if your tires are not cold.)
Because tires are designed to be used on more than one type of
vehicle, tire manufacturers list the “maximum permissible inflation
pressure” on the tire sidewall. This number is the greatest amount
of air pressure that should ever be put in the tire under normal
driving conditions.
CHECKING TIRE PRESSURE
It is important to check your vehicle’s tire pressure at least once a
month for the following reasons:
•
Most tires may naturally lose air over time.
•
Tires can lose air suddenly if you drive over a pothole or other
object or if you strike the curb when parking.
•
With radial tires, it is usually not possible to determine under-
inflation by visual inspection.
For convenience, purchase a tire pressure gauge to keep in your
vehicle. Gauges can be purchased at tire dealerships, auto supply
stores, and other retail outlets.
The recommended tire inflation pressure that vehicle
manufacturers provide reflects the proper psi when a tire is cold.
The term cold does not relate to the outside temperature. Rather,
a cold tire is one that has not been driven on for at least three
hours. When you drive, your tires get warmer, causing the air
pressure within them to increase. Therefore, to get an accurate
tire pressure reading, you must measure tire pressure when the
tires are cold or compensate for the extra pressure in warm tires.
STEPS FOR MAINTAINING PROPER
TIRE PRESSURE
1. Locate the recommended tire pressure on the vehicle’s tire
information placard, certification label, or in the owner’s
manual.
2. Record the tire pressure of all tires.
3. If the tire pressure is too high in any of the tires, slowly
release air by gently pressing on the tire valve stem with the
edge of your tire gauge until you get to the correct pressure
4. If the tire pressure is too low, note the difference between
the measured tire pressure and the correct tire pressure.
These “missing” pounds of pressure are what you will need
to add.
5. At a service station, add the missing pounds of air pressure
to each tire that is underinflated.
6. Check all the tires to make sure they have the same air
pressure (except in cases in which the front and rear tires
are supposed to have different amounts of pressure).
If you have been driving your vehicle and think that a tire is
under-inflated, fill it to the recommended cold inflation pressure
indicated on your vehicle’s tire information placard or certification
label. While your tire may still be slightly under-inflated due to the
extra pounds of pressure in the warm tire, it is safer to drive with
air pressure that is slightly lower than the vehicle manufacturer’s
recommended cold inflation pressure than to drive with a
significantly under-inflated tire. Since this is a temporary fix, don’t
forget to recheck and adjust the tire’s pressure when you can
obtain a cold reading.
TIRE SIZE
To maintain tire safety, purchase new tires that are the same size
as the vehicle’s original tires or another size recommended by the
manufacturer. Look at the tire information placard, the owner’s
manual, or the sidewall of the tire you are replacing to find this
information. If you have any doubt about the correct size to
choose, consult with the tire dealer.
TIRE TREAD
The tire tread provides the gripping action and traction that
prevent your vehicle from slipping or sliding, especially when the
road is wet or icy. In general, tires are not safe and should be
replaced when the tread is worn down to 1/16 of an inch. Tires
have built-in tread wear indicators that let you know when it is
time to replace your tires. These indicators are raised sections
spaced intermittently in the bottom of the tread grooves. When
they appear “even” with the outside of the tread, it is time to
replace your tires. Another method for checking tread depth is to
place a penny in the tread with Lincoln’s head upside down and
facing you. If you can see the top of Lincoln’s head, you are ready
for new tires.
