The two most important factors in selecting towing equipment are gross trailer weight (GTW) and tongue weight (TW).


For the Trailer
Gross trailer weight (GTW) is the weight of the trailer fully loaded in its actual towing condition. GTW is measured by placing the fully loaded trailer on a vehicle scale. The entire weight of the trailer should be supported on the scale as shown in Figure 1.

1. Tongue weight (TW) is the downward force exerted on the hitch ball by the trailer coupler. In most cases, it is about 10 to 15 percent of GTW. TW of up to 300 lbs. can be measured on a household scale by resting the trailer coupler on the scale and placing the scale on a box so that the coupler is at its normal towing height. The trailer must be fully loaded and level.

For heavier tongue weights, place a household scale and a brick that's as thick as the scale three feet apart as shown in Figure 2. Set a length of pipe on each and rest a beam across the pipes. Re-zero the scale to correct for the weight of the beam and pipe. Securely block the trailer wheels. Rest the trailer jack on the bream as shown, one (1) foot from the brick and two (2) feet from the scale.

To obtain the TW, multiply the scale reading by three (3). For greater tongue weights, place the scale and brick four (4) feet apart, rest the jack on the beam three (3) feet from the scale and multiply the scale reading by four (4).


For the Tow Vehicle
Like the trailer, the tow vehicle has a maximum weight capacity it was designed to tow. Its maximum towing capacity can be found in the owner's manual.


Your Towing Equipment
Trailer Hitches, Receivers, and Ball Mounts
Select these products by their gross trailer weight and tongue weight ratings. Select hitches and receivers for specific vehicles. There are two types of trailer hitches:
1. Weight-carrying hitches
2. Weight-distributing hitches

Weight-carrying hitches are by far the most popular and carry all the trailer tongue weight directly on the rear of the vehicle. They are commonly used to tow small and medium-sized trailers.

Weight-distributing hitches are usually recommended for heavier trailers because they even out the trailer load between the wheels of the tow vehicle and the wheels of the trailer, thus improving steering and braking control. Tow parts are required: the receiver, which bolts to the vehicle, and the spring bar assembly.

Before deciding which type if right for you, consult your car or truck manual for the manufacturer's recommendation and the load capacity of your vehicle.

Hitch Balls
Select hitch balls by GROSS TRAILER WEIGHT rating, mounting platform thickness and hole size, and to match the coupler socket size.

Couplers
The trailer coupler socket should be smooth, clean and lightly lubricated. Tighten or adjust to prevent excess play, but not enough to bind on the ball. Check the coupler manufacturer's instructions.

Safety Chains
Cross chains under coupler and attach to hitch or towing vehicle. Allow just enough slack to permit full turning. Don't let chains drag on the road. Secure connections so they can't bounce loose. CONNECT CHAINS EVERY TIME YOU TOW.

Sway Controls
Sway controls can lessen the effects of sudden maneuvers, wind gusts and buffeting caused by other vehicles. We recommend them for trailers with large surface areas, such as travel trailers. They are also helpful for trailers with low tongue weight percentage.

Other Useful Equipment
AIR SPRINGS, AIR SHOCKS or HELPER SPRINGS are useful for weight-carrying hitch applications. A TRANSMISSION COOLER may be necessary for heavy towing. Many states require TOWING MIRRORS on both sides.