Car Trailer Basics 101, Part II

What you need to know to buy your next trailer

Rich Lagasse Apr 7, 2008 0 Comment(s)
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This details the optional weight distribution and dual-cam sway setup that can be added to your trailer.

We began the subject of car trailers in last month's issue and addressed the basic types of trailers, size, major manufacturers, options, and pricing. In this month's installment, we will address the tow vehicle, hitch setup, towing safety, several driving tips, useful items to have handy, maintenance, insurance, and other options to consider.

The type of tow vehicle that will work best for you depends on the total weight of the car being hauled, the trailer, and any cargo, as well as the type of terrain you will be covering. Typically, manufacturers' tow vehicle ratings specify the trailer tongue weight, as well as the weight of the combined and fully loaded weights at which a tow vehicle can safely tow a trailer. These ratings are usually the maximum allowable weights. Some of the terms you will find are:

- Gross Vehicle Weight Rating (GVWR): Weight for a fully loaded vehicle itself.
- Towing Capacity: Weight a vehicle can tow. This can depend on the vehicle's equipment and type of hitch used.
- Gross Combination Weight Rating (GCWR): Combined weight of the tow vehicle, trailer, passengers, equipment, fuel, and so on that the vehicle can handle.
- Gross Axle Weight Rating (GAWR): Weight a single axle can handle.
- Tongue Weight: The weight of the trailer on the trailer hitch. Not enough tongue weight can cause the trailer to sway, while too much can cause reduced steering response. This is where a weight distributing hitch can help by transferring weight more evenly on both axles of the tow vehicle.

Trailers also have a Gross Vehicle Weight Rating for the weight of the trailer and its contents, and a Gross Axle Weight Rating for the rating of its axles.

We have had several tow vehicles, but found a three-quarter-ton truck to work well. The one we now have is a Silverado 2500HD with the Duramax diesel and Allison transmission. The towing performance, stability, and fuel mileage have been super. Just set the cruise control and let it do the work. Hills are a non-issue with this tow vehicle, which makes driving much more relaxing.

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This trailer setup uses a bumper-style setup, which is the more common attachment mode.

While there are two main types of hitch styles-bumper mount or fifth-wheel-we'll address the bumper style since that is the most common. For the bumper style, the major consideration is the rating of the hitch, use of a weight distribution setup, and the sway control. The hitch should be a Class IV or V with a weight distributing setup. Adjusting the tension on the weight bars is also important, as is setting the height at the hitch ball. The trailer should be very close to level when loaded with the car. Otherwise, you can experience some sway. If you can't get it perfectly level, it's better to have the height at the trailer hitch a tad (1-inch) higher than the top of the tow vehicle ball. You can get ball mounts, which are adjustable to get the ball at the right height. If you do experience sway while driving, any steering corrections you make should be small and slow. Sometimes applying the trailer brakes alone (by using the lever on the brake controller) will help correct the sway.

For the sway control we use a dual-cam-style. Reese and Draw-Tite are two of the better known makes. One model to look for is the Reese PN 26002 and Draw-Tite PN 26000. There is also a single arm friction sway control, such as the Reese PN 26660, but we prefer the dual unit. Another hitch company is Equalizer.

Web sites:

You also need a good brake controller. We now use the Tekonsha Prodigy unit, which works well. Some vehicles with the trailer towing option are setup for this controller and allow you to plug right into their pre-installed harness, using the appropriate adaptor harness, which simplifies the setup. The controllers are adjustable for when the trailer brakes come on, as well as the amount of braking. I set the unit to come on just ahead of the truck brakes and with enough pull to feel it working while not locking the brakes. This is especially important in wet or slippery driving conditions. The Tekonsha web site is, and there are many other makes available.

Your tow vehicle will need camper-style mirrors. Many varieties are available from those that clip onto your existing mirrors to those specifically designed for towing. Some trucks are now available with power mirrors, which extend for towing and work great. Even with the widest mirrors, they won't necessarily give you full view along the side of the wide-bodied trailers when backing up, but they are essential for safe driving. We also use small spot mirrors, which help remove the blind spots.

Federal law requires trailers to have taillights, brake lights, side marker lights, turn signals, and side and rear reflectors. Some trailers use a four-way connector hooked into the tow vehicle's electrical system. Many use a seven-way connector that includes an electric brake signal, power supply, and backup lights, in addition to the typical four functions. Your trailer supplier will be able to ensure the tow vehicle and trailer are compatible.

How well you can handle and control your tow vehicle and trailer is heavily influenced by how well the cargo is loaded and distributed. For safe towing, it's best to balance the weight along the length of the trailer, as well as side to side.

Most state or federal laws require safety chains or cables, as well as a break-away switch. The safety chains should be crisscrossed, allow enough length so as not to bind when turning, but not drag on the ground. The break-away switch connects by a small cable to the hitch and, should the trailer become disconnected from the tow vehicle, the cable pulls a plug that applies the electric trailer brakes.

When hooking up or unhooking your trailer, be sure to first chock the tires both front and rear to keep it in place and to keep you safe. In addition to tire chocks, you may also want to consider one of the many tire locks available, which place pressure on both tires. Camping stores have a few different types.

Before you leave for a trip, it's important to check the tire pressures on the trailer, as well as the tow vehicle. On the latter, we increase the tire pressure when towing. Check your owner's manual for their suggestions. Also, check the position of the side mirrors, ensure the safety chains and electrical connections are in place, as well as the operation of all your lights. Double-check the car is tied down securely, that there's no gear to move around inside the trailer, and that the trailer doors are locked.




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