Operating Guide

35
4.5 tongue weIght
It is critical to have a portion of the trailer load carried
by the tow vehicle. That is, the trailer tongue must exert
a downward force on the hitch. This is necessary for
two reasons. First, the proper amount of tongue weight
is necessary for the tow vehicle to be able to maintain
control of the tow vehicle/trailer system. If, for example,
the tongue exerts an upward pull on the hitch, instead
of pushing down on it (because the trailer is overloaded
behind its axle(s)), the rear wheel of the tow vehicle
can lose traction or grip and cause loss of control. Also,
even if there is some weight on the tongue, but not
enough weight on the tongue, the trailer can become
unstable at high speeds. Remember, the faster you go
the more likely the trailer is to sway.
If there is too much tongue weight, the tow vehicle is
prone to jack-knife. The front wheels of the tow vehicle
can be too lightly loaded and cause loss of steering
control and traction, if the front wheels are driving.
In addition to tow vehicle control, tongue weight
is necessary to insure that the trailer axle(s) do not
exceed their Gross Axle Weight Rating (GAWR).
In the following table, the second column shows the
rule of thumb percentage of total weight of the trailer
plus its cargo (Gross Trailer Weight, or “GTW”) that
should appear on the tongue of the trailer. For example,
a large trailer with a loaded weight of 6,000 pounds,
should have 10-15% of 6,000 pounds (600-900 lbs.)
on the hitch.
Tongue Weight as a Percentage of Loaded Trailer
Weight
Type of Hitch Percentage
Ball Hitch or
Ring & Pintle
10-15% for large trailers
6-10% for small trailers
The numbers quoted are for example purposes only
and should be tailored to the specic trailer.
For questions regarding the actual percent of tongue
weight for the trailer, check with the manufacturer
for specics.
^ WARNING
Improper tongue weight (load distribution)
can result in loss of control of the trailer,
leading to death or serious injury.
Make certain that tongue weight is within
the allowable range.
Be sure to:
• Distribute the load evenly, right and left.
• Keep the center of gravity low.
• Distribute the load front-to-rear to provide
proper tongue weight (see chart).
A owable load must be evenly distributed
throughout the body.
4.5.1 checkIng tongue weIght
To check the tongue weight, the tow vehicle and trailer
must be on level ground, as they will be when the trailer
is being towed.
Take the trailer to a truck stop or grain elevator where
there is a “certied” scale. Place the tow vehicle only
onto the scale and get the weight. This weight must be
less than your tow vehicle’s GVWR.
Pull the trailer onto the scale and uncouple it from the
tow vehicle, leaving just the trailer on the scale. Get a
ticket which lists the total trailer weight. Re-connect the
trailer to your tow vehicle and the drive the tow vehicle
wheels off the scale, just leaving the trailer axles on the
scale. Get a “ticket”, which lists the trailer’s axle weight.
Simply subtract the axle weight from the total weight to
determine the hitch weight.
While you are at the scale, you should weigh the entire
combination vehicle. This result should be less than
the Gross Combined Weight Rating (GCWR) for your
towing vehicle. Some scales allow you to get individual
axle weights also. If this is possible, get the tow vehicles
front and rear axle weights to make sure they are in the
same proportion as the tow vehicle alone, and that the
rear axle is not overloaded.
Coupling To Tow Vehicle