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1.5.2. Understanding Tire Pressure and Load Limits
Tire inflation 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 inflation pressure is a number that indicates the amount of air
Pressure-measured in pounds per square inch (psi) -a tire requires to be properly inflated. (you will also find
this number on the vehicle information placard expressed in kilopascals (kpa), which is the metric measure
used internationally)
Manufacturers of passenger vehicles and light truck determined this number based on the vehicle’s design load
limit, that is , the greatest amount of weight a vehicle can safely carry and the vehicles 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 manufactures 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.
1.5.3. Checking Tire Pressure
It is important to check your vehicle’s tire pressure at least once a month for the following reasons:
Most tire may naturally lose air over time
Tire can lose air suddenly if you drive over pothole or other object or if you strike the curb when
parking.
With radial tires, it is usually not possible to determine underinflation by visual inspection
For convenience, purchases 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 and accurate tire pressure reading, you must measure tire pressure when the tires
are cold or compensate for extra pressure in warm tires.
1.5.4. Steps For Maintaining Proper Tire Pressure
Step 1: Locate the recommended tire pressure on the vehicle’s tire information
placard, certification label, or the owner’s manual.
Step 2: Record the tire pressure of all tires
Step 3: If the tire pressure is to high in any of the tires, slowly release air by gently pressuring on
the tire valve stem with the edge of your tire gauge until you get to the correct pressure
Step: 4: If the tire pressure is too low, note the difference between the measured and the correct tire
pressure. These “missing” pounds of pressure are what you will need to add
Step 5: At a service station, add the missing pounds of air pressure (except in cases in which the
front and rear tires are supposed to have different amounts of pressure)
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