Trailer Owner’s Manual

5 Outfitting the Tow Vehicle and Trailer

Throughout this manual, the phrase “tow vehicle” refers to the truck or car which is being used to pull the trailer.

5.1 Weight Ratings

Your tow vehicle and trailer each has its own ratings regarding maximum weights and capacities. These ratings are found in the owner’s manual, and also on a label which is usually found in the door frame.

Not all vehicles are rated to safely pull all trailers. Consult your vehicle’s manual to see if it is recommended to be able to pull your trailer. Pay special attention to the tow capacity rating for the tow vehicle. Your vehicle should be rated to pull the weight of the trailer plus any cargo, water, propane tanks, and batteries. This is the first item listed below.

The following explains some of the factors which are involved. See Figure 1.

Gross Trailer Weight Rating (Tow Capacity) — GTWR:

The maximum trailer weight that the tow vehicle is rated to pull. This rating can depend on factors such as front- or rear-wheel drive, engine and transmission choices, differential gearing, strength of the hitch-to-frame attachment points, or heavy-duty suspension options. A separate rating may be given for a trailer with or without its own trailer brakes. Find this number in your tow vehicle’s manual.

Gross Vehicle Weight Rating — GVWR:

The maximum weight of the tow vehicle, including all passengers and cargo, plus the hitch weight (listed below). This is the maximum total weight that can be carried by the tow vehicle’s springs.

Gross Combined Weight Rating — GCWR:

The maximum weight of the tow vehicle, including all passengers and cargo, plus the trailer, including all cargo. This is the maximum total weight which must be stopped by the brakes.

Hitch Weight Rating — HWR:

Maximum weight that the hitch may carry. The trailer places some of its own weight onto the hitch, and this weight is carried by the tow vehicle. Find this number on the hitch itself.

Trailer Gross Vehicle Weight Rating — TGVWR:

Maximum weight of the trailer plus its own cargo. This is the maximum weight which the trailer springs may carry, and is determined by the trailer suspension springs, axle, and tires.

Trailer Cargo Capacity — TCC:

Maximum cargo weight which the trailer may carry. This is trailer gross vehicle weight rating minus its actual unloaded weight. The difference is the amount of cargo which can be carried by the trailer before it reaches its own gross vehicle weight rating.

Figure 1: Weight Ratings


5.2 Hitch and Hitch Ball Selection

See Figure 8 (Hitch, Draw Bar, and Receiver) for a diagram of the hitch, hitch ball, draw bar, and receiver.

Your trailer requires a 2″ hitch ball, mounted to a draw bar which is then mounted in the receiver. The draw bar lowers or raises the hitch ball to a height which results in the trailer being close to level or leaning slightly to the front once it is connected to the tow vehicle.

A sway control hitch is usually not necessary. Sway can usually be controlled by proper positioning of the cargo load in the trailer. See Section 6.5 (Packing the Trailer and Tow Vehicle) for details.

A weight distributing hitch helps take weight off the back end of the tow vehicle, and it might be required for a small tow vehicle to carry the hitch weight of your trailer. Consult your dealer for details.

5.3 Hitch Electrical Connection

Tow vehicles which have been prepared with a trailer towing package commonly have either a flat four-pin socket or else a round seven-pin socket located either near or on the receiver hitch. The four-pin socket provides connections for basic lights ( running, turn signal, and stop ), but not for reverse lights, battery charging, or electric brakes. Adapters are available to connect your seven-pin cable to a vehicle with a four-pin socket, but only the basic light functions will work.

A seven-pin socket and its associated wiring is greatly desirable for trailer towing due to the extra functions which are provided. It is worth having the hitch connector rewired if necessary to provide the full seven-pin functions, especially the trailer’s electric brake control. See your dealer for details.

See Figure 19 (Trailer Cable — Wiring Example) for the functions of the trailer’s electrical connection, and Figure 20 (Trailer Cable Plug — Pin Assignments) for the connector plug’s pin assignments.

5.4 Brake Controller

When the trailer has electric brakes, the tow vehicle must have a brake controller installed to active the trailer brakes. The brake controller applies the trailer brakes when it senses the tow vehicle is slowing down. A better-quality brake controller results in smoother and more accurate application of the trailer brakes, which can mean shorter stops in an emergency.

While choosing a brake controller, look for an electronic “inertial” controller which senses how hard the tow vehicle is stopping, and applies trailer brakes in a similar amount. These controllers help resist skidding and sliding on gravel, snow, or ice. The controller is adjustable, and should be set such that on dry pavement during a hard stop the trailer is just about to skid, but does not. This results in maximum braking assist while still maintaining control. Consult the controller’s owner’s manual for details.

5.5 Tow Mirrors

In many states, it is a requirement that the driver be able to see around the sides of the trailer. If the trailer is too wide for the driver to see around using the tow vehicle’s regular side mirrors, then special towing mirrors should be installed. These mirrors extend further out to the side than the regular mirrors. Tow mirrors not only meet state requirements, but are also very helpful for backing the trailer into a campsite. See your dealer for details.

5.6 Trailer Jack and Lug Wrench

You must have a jack capable of lifting the trailer, along with a lug wrench which fits the trailer’s lug nuts.

Test any jack before starting a trip, to verify that it can actually lift the trailer high enough to change a tire.

The trailer’s stabilizer jacks are not meant to be used to lift the trailer. A dedicated jack must be used instead.

To assist in loosening lug nuts which have been over tightened by a tire shop, it is very useful to purchase a 24″ long 1 ⁄2″ drive flex handle (“breaker bar”) plus a 3″ extension and a deep-well socket which fits the lug nuts. These tools allow you to easily remove almost any stubborn lug nut.

While replacing and tightening the lug nuts, a 1 ⁄2″ drive torque wrench plus the same 3″ extension and deep-well socket allow you to tighten the lug nuts up to the correct amount of torque, without over tightening. This ensures that the lug nuts are properly tight, eliminates the risk of breaking a lug nut, allows much easier removal at a later time, and can extend brake life and reduce brake shudder which can come from uneven torque at the lug nuts. See Figure 2.

A “click-stop” torque wrench is faster and more convenient to use than a “beam” style wrench. Be sure to reduce the click-stop torque setting back to the low end of the range before storing the torque wrench. See Figure 3.

See an automotive parts store or hardware store for a flex handle, torque wrench, extension, and deep-well socket.

Figure 2: Flex Handle (“Breaker Bar”), Extension, Deep-Well Socket


Figure 3: Click-Stop Style Torque Wrench


5.7 Leveling Tools and Wheel Chocks

Various tools are used to level the trailer and then keep it from moving. The trailer’s built-in hitch jack is used to level the trailer from front-to-back, but other tools must be used to level the trailer from side-to-side. The trailer’s stabilizer jacks are not made for this purpose; they are only designed to keep the trailer steady once it has been set up.

Tools for side-to-side leveling include step ramps made of plastic or wood, interlocking plastic blocks, and a wheel-grabbing screw jack called the “BAL Leveler”.

Stacks of wood can be made of 6″ wide lumber, either 1″ or 2″ thick. Use pieces of wood which are long enough to drive onto while still leaving room for wheel chocks on both sides of the wheel. If stacking two pieces, use a longer piece for the lower level to allow a ramp to be built up to the upper level. Use pressure treated lumber for extra strength.

Multilevel plastic step ramps are available, allowing you to pull forward until the correct height is obtained. This will require the help of an assistant to tell you exactly where to stop, and a wheel chock will have to be set against the down-hill side of the wheel to keep the trailer in place.

Interlocking plastic blocks are available, and they allow you to create a ramp of just the right height, with a built-in wheel stop in addition.

The “BAL Leveler” is a metal U-shaped jacking device which grabs the wheel securely, then raises it with a screw and ratchet until the desired height is obtained, doubling as an excellent wheel chock. The device requires that the screw be kept clean and greased often, and it is rather large to carry and store, but it can be very handy in many situations.

Wheel chocks are available made of plastic, rubber, or metal. Plastic wheel chocks can work, but rubber wheel chocks are better at resisting slipping. Be sure to get wheel chocks which closely match the size of the tire. Wheel chocks which are made for a much larger tire will not wrap as well against a smaller tire, resulting in less gripping force.

Folding metal wheel chocks can work, but are more likely to slide, and can collapse if accidentally driven over.

5.8 Electrical Testers

The campground’s 120 V ac electrical system should be tested before plugging in the trailer.

An outlet wiring tester is plugged into the outlet and has three lights which display a pattern to indicate proper wiring or one of several possible problems, such as a missing ground or a reversed hot and neutral. This inexpensive tester is available at a hardware store. See Figure 4.

An ac voltmeter plugs into the outlet and shows you the actual voltage present at the socket. Meters are available from R/V parts vendors which show the range of acceptable voltage for an R/V air conditioner. Volt meters are also available which use test probes instead of a 120 V ac outlet plug, but for convenience it is recommended that you purchase a voltmeter which plugs directly into the outlet.

Figure 4: AC Outlet Wiring Tester


5.9 Water Pressure Regulator

A campground water supply sometimes may have too much pressure for the trailer’s plumbing. See an R/V dealer for a water pressure regulator which screws into the fill hose to reduce the water pressure before it goes into the trailer. A short section of hose plus a right angle adapter can be useful to go between the regulator and the trailer’s city water connection. See Figure 13 (Shore Water Connection).

The pressure regulator is only required when connecting the trailer directly to the water supply, but is not required when simply using a hose to fill water into the fresh water tank.