Ditch Witch FX20 - Manual (Page 98)

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 trailer. The tire inflation pressure is a number that indicates
the amount of air pressure– measured in pounds per square inch (psi) or kilopascals (kpa) –a tire
requires to be properly inflated.
This number based on the trailer's design load limit, that is, the greatest amount of weight a trailer
can safely carry and the tire size. The proper tire pressure for your trailer 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.
1.5.3. CHECKING TIRE PRESSURE
It is important to check your trailer'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 underinflation by visual inspection.
For convenience, purchase a tire pressure gauge to keep with your trailer. Gauges can be
purchased at tire dealerships, auto supply stores, and other retail outlets.
The recommended tire inflation pressure that 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.
1.5.4. STEPS FOR MAINTAINING PROPER TIRE PRESSURE
Step 1: Locate the recommended tire pressure on the trailer's tire information placard,
certification label, or in the owner's manual.
Step 2: Record the tire pressure of all tires.
Step 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.
Step 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.
Step 5: Add the missing pounds of air pressure to each tire that is underinflated.
Step 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 towing your trailer and think that a tire is underinflated, fill it to the recommended
cold inflation pressure indicated on your trailer's tire information placard or certification label.
While your tire may still be slightly underinflated 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 recommended cold inflation
pressure than to drive with a significantly underinflated 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.