Tongue Weight (TW)
The tongue weight is the downward force exerted on the
hitch ball by the trailer. You must consider this as part of
the load on your vehicle.
Trailer Frontal Area
The frontal area is the maximum height multiplied by the
maximum width of the front of a trailer.
Trailer Sway Control
The trailer sway control can be a mechanical telescoping
link that can be installed between the hitch receiver and the
trailer tongue that typically provides adjustable friction
associated with the telescoping motion to dampen any
unwanted trailer swaying motions while traveling.
If equipped, the electronic Trailer Sway Control (TSC)
recognizes a swaying trailer and automatically applies
individual wheel brakes and/or reduces engine power to
attempt to eliminate the trailer sway.
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 kinds ofhitches 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 leverage
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 manufacturer’s directions, it provides
for a more level ride, offering more consistent steering and
brake control thereby enhancing towing safety. The addi-
tion 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.
6
STARTING AND OPERATING 177
Tire Sizing Chart
EXAMPLE:
Example Size Designation: P215/65R15XL 95H, 215/65R15 96H, LT235/85R16C, T145/80D18 103M, 31x10.5 R15 LT
P = Passenger car tire size based on U.S. design standards, or
....blank.... = Passenger car tire based on European design standards, or
LT = Light truck tire based on U.S. design standards, or
TorS= Temporary spare tire or
31 = Overall diameter in inches (in)
215, 235, 145 = Section width in millimeters (mm)
65, 85, 80 = Aspect ratio in percent (%)
–Ratio of section height to section width of tire, or
10.5 = Section width in inches (in)
R = Construction code
–R means radial construction, or
–D means diagonal or bias construction
15, 16, 18 = Rim diameter in inches (in)
Service Description:
95 = Load Index
–A numerical code associated with the maximum load a tire can carry
258 SERVICING AND MAINTENANCE
