DRIVING & SAFETY — 2
22
20 08 CONTESSA
Calculating Tow Capacity:
Several variables must be reviewed and
calculated to properly determine towing
capacity. Limiting factors include GCWR
(Gross Combination Weight Rating), GAWR
(Gross Axle Weight Rating), hitch receiver
weight rating and the weight rating of each
piece of towing equipment. One or some of
these variables will limit tow capacity.
Example: The tow vehicle has a GCWR
of 35,000 lbs. The tow vehicle in a fully
loaded, ready for travel condition, weighs
29,500 lbs. The hitch receiver is rated at
700 lbs. tongue, 7000 lbs. tow. The load
being towed weighs 4,200 lbs. with a
tongue weight of 400 lbs. However, the
hitch ball is rated at 3,500 lbs. In this case
tow capacity is limited to 3,500 lbs. due
to the rating of the hitch ball, even though
the rest of the towing equipment, hitch
receiver and vehicle GCWR are within
specications.
It is possible to be within the GCWR but
exceed the GAWR. When tongue weight is
applied, mechanical advantage increases with
distance (lever) from the hitch ball to the tag
axle. The tag axle now becomes a pivot point
(fulcrum). As tongue weight increases (effort),
weight on the tag axle also increases (fulcrum)
while weight on the front axle decreases (load)
as weight is displaced from the front axle.
It may be necessary to weigh both the tow
vehicle and towed load as an assembly to ensure
the GAWR has not been exceeded.
NOTE:
It may be necessary to adjust the tag
axle pressure regulator to compensate
for tongue weight.
It is also possible to be within the rating of the
hitch receiver and yet exceed the GCWR.
Due to changes in weight, the motorhome
must be weighed in a loaded, ready for travel
condition that includes passengers, cargo and
liquids. Subtract the weight of the motorhome
in a loaded, ready to travel condition from the
GCWR to determine tow capacity. Whether
towing a vehicle or trailer, the load being towed
must be weighed to ensure the towed weight,
when added to the tow vehicle, will not exceed
the GCWR and the weight ratings of each tow
system component are equal to or greater than
the load being towed.
WARNING:
The motorhome and towed load must be
weighed after they are loaded for travel
to determine if actual weights are within
towing specification. Each component of
the towing system must be rated equal
to or greater than the load being towed.
Do not exceed the Gross Combination
Weight Rating.
090512c
GAWR GAWR Tow Weight
Tongue
Weight
090512
Ball Mount
Weight Rating
Hitch Ball
Weight Rating
090512b
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