Jeep Grand Cherokee 2012 Owner's Manual page 486

Tongue Weight (TW)
The tongue weight is the downward force exerted on the
hitch ball by the trailer. In most cases it should not be less
than 10% or more than 15% of the trailer load. You must
consider this as part of the load on your vehicle.
Frontal Area
The frontal area is the maximum height and maximum
width of the front of a trailer.
Weight-Carrying Hitch
A weight-carrying hitch supports the trailer tongue
weight, just as if it were luggage located at a hitch ball or
some other connecting point of the vehicle. These kind of
hitches are the most popular on the market today and
they are commonly used to tow small- and medium-
sized trailers.
Weight-Distributing Hitch
A weight-distributing system works by applying lever-
age through spring (load) bars. They are typically used
for heavier loads, to distribute trailer tongue weight to
the tow vehicle's front axle and the trailer axle(s). When
used in accordance with the manufacturers' directions, it
provides for a more level ride, offering more consistent
steering and brake control thereby enhancing towing
safety. The addition of a friction/hydraulic sway control
also dampens sway caused by traffic and crosswinds and
contributes positively to tow vehicle and trailer stability.
Trailer sway control and a weight distributing (load
equalizing) hitch are recommended for heavier Tongue
Weights (TW) and may be required depending on Vehicle
and Trailer configuration/loading to comply with gross
axle weight rating (GAWR) requirements.
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