HOW TO DETERMINE GTW & TW CAPACITES

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

To select the right hitch, you need information about the tow vehicle and trailer.

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.

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 beam 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.

Determine GTW & TW with this convenient chart.