Operating Guide

22
• Uniform Tire Quality Grading System
• Fundamental characteristics of tires
• Tire safety tips.
Use this information to make tire safety a regular part
of your vehicle maintenance routine. Recognize that
the time you spend is minimal compared with the
inconvenience and safety consequences of a at tire
or other tire failure.
3.5.1 Safety fIrSt- BaSIc tIre maIntenance
Properly maintained tires improve the steering,
stopping, traction, and load-carrying capability of your
vehicle. Underinated tires and overloaded vehicles are
a major cause of tire failure. Therefore, as mentioned
above, to avoid at tires and other types of tire failure,
you should maintain proper tire pressure, observe
tire and vehicle load limits, avoid road hazards, and
regularly inspect your tires.
3.5.2 fIndIng your VehIcle’S recommended tIre
preSSure and load lImItS
Tire information placards and vehicle certication labels
contain information on tires and load limits. These
labels indicate the vehicle manufacturer’s information
including:
• Recommended tire size
• Recommended tire ination pressure
• Vehicle capacity weight (VCW–the maximum
occupant and cargo weight a vehicle is designed
to carry)
• Front and rear gross axle weight ratings (GAWR–
the maximum weight the axle systems are designed
to carry).
• Both placards and certication labels are
permanently attached to the trailer near the left
front.
3.5.3 underStandIng tIre preSSure and load
lImItS
Tire ination pressure is the level of air in the tire that
provides it with load-carrying capacity and affects the
overall performance of the vehicle. The tire ination
pressure is a number that indicates the amount of
air pressure– measured in pounds per square inch
(psi)–a tire requires to be properly inated. (You will
also nd this number on the vehicle information placard
expressed in kilopascals (kPa), which is the metric
measure used internationally.)
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 ination pressure.” (As you will
read below, it is difcult 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 ination 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.
3.5.4 Safety fIrSt- BaSIc tIre maIntenance
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 ination 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 ination pressure that
vehicle manufacturers provide reects 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.
3.5.5 StepS for maIntaInIng proper tIre
preSSure
1. Locate the recommended tire pressure on the
vehicle’s tire information placard, certication 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
Tire Safety