Hauling Heavy Loads
Truck drivers need to take utmost care when hauling heavy loads.
They need to consider the load carrying capacity of their vehicle.
Overloading can have serious consequences in terms of safety. Too much
weight for your vehicle's suspension system can cause spring, shock
absorber or brake failure, handling or steering problems, irregular
tire wear, tire failure or other damage. An overloaded vehicle is hard
to drive and hard to stop. Brakes can completely fail, particularly on
steep hills on an overloaded vehicle. A combination of size of the tire
and the corresponding inflation pressure determine the load that tire
can carry safely. Overloading the truck, with under inflated tires, can
be perilous. Abnormal tire flexing takes place due to overloading. This
generates excessive heat within the tire that may exceed the tire's
capacity and lead to tire failure. The air pressure enables a tire to
support the load, therefore proper inflation is critical.
Trucks can be loaded in many different ways; air pressures must be
determined from the actual loads (determined by weighing) and taken
from the load and inflation tables provided by the tire manufacturer.
However, they should never exceed the tire limitation for load or air
pressure. If you discover that your tires cannot support the actual
weights, lighten the load or install tires with a higher carrying
It should be noted that installing tires with a higher carrying
capacity only solves the problem of tire overload. It has no effect on
the overloading of other components (i.e., rims, axles, shocks, or
bearings). Rims may not be capable of withstanding the higher pressures
necessary to support the load. If you decide to install a tire size
other than that originally provided on the vehicle, care must be taken
to ensure adequate load-carrying capacity and compatibility between the
tire and rim. There is a danger of serious injury or death if a tire of
one bead diameter is installed on a rim or wheel of a different rim
diameter. Always replace a tire with another tire of exactly the same
bead diameter designation and suffix letters.
If you have operated your vehicle with an underinflated tire, promptly
have it removed from the wheel for a complete internal inspection to be
sure it is not damaged. Tires driven even short distances while
underinflated may be damaged beyond repair.
Tires should be inspected regularly for excessive or irregular
treadwear, bulges, aging, fabric breaks, cuts or other damages. Remove
any nails, stones, glass, etc., embedded in the tread to prevent
damage. Even minor damage can lead to tire failure. Replace tires when
the tread is worn to 2/32" depth remaining in two or more adjacent
On vehicles with GVWR in excess of 10,000 pounds, federal regulations
require that tires on the front axle be removed when worn down to 4/32"
depth. It may also be desirable to replace tires prior to wearing down
to 4/32" to improve traction or vehicle handling. If your tires show
uneven wear, ask a serviceperson to check for and correct any
misalignment, imbalance, or other mechanical problem involved. Check
your tires frequently for scrapes, bulges, cuts, snags, or impact
damage. Damage can occur to the inner portions of your tire without
being visible on the outside. While driving, if you experience a sudden
vibration or ride disturbance, or if you suspect that damage to your
tires or vehicle has occurred, immediately reduce your speed or stop.
Drive with caution or have your vehicle towed to the nearest vehicle or
tire dealer to have your vehicle inspected.