Safe towing requires an understanding of trailer and tow vehicle capabilities, as well as proper loading and safety checks. First, you need to ensure the trailer is up to the task. The gross vehicle weight rating (GVWR) is printed on a label or placard - often referred to as the certification or VIN label - mounted on the left front side of the trailer, typically within 6 inches of the floor line or near the coupler. The GVWR is the maximum a trailer should ever weigh when loaded.
The gross axle weight rating (GAWR) is also listed on the certification label. According to the Trailer Safety Industry Coalition (TISC), this indicates the most weight an axle can bear. If the trailer has more than one axle, each axle will have weight rating information provided on the certification label.
Next, you must realize that not all trailers are constructed the same. Make sure there are sufficient crossmembers underneath the trailer to support the specific load you plan to haul.
"I had a complaint where a customer bought a 7,000-lb. GVW car hauler trailer and used it to haul a skid loader," says Clint Lancaster, National Association of Trailer Manufacturers (NATM). "Even though that trailer was within its weight capacity, it wasn't designed for that piece of equipment. It was designed for a car that has more dispersed weight. Equipment has very concentrated areas of weight."
Weight distribution on a trailer is critical to safe performance. "If you get too much of the load on the front, it is going to cause the tow vehicle to be unstable and it may cause under-steer or jackknifing," says Lancaster. "If you get too much on the back and start to lift the rear end of the tow vehicle, that causes trailer instability and swaying. The tow vehicle needs to be level. The front end of the truck should come back down to a level position."
Don't put excessive weight on the trailer tongue. Lancaster advises a 10% to 15% tongue weight for bumper pull trailers and 20% to 25% for goosenecks and fifth wheels.
Take the time initially to understand where the equipment should be loaded. "Many times I will put a stop on the trailer," Lancaster notes. This is a piece of angle iron that tells the operator where the vehicle being loaded needs to stop. It can be made to clip on so it can be easily removed if you need to move other equipment.
In addition, don't place excessive weight on either side of the trailer. If you do, the tire weight ratings on the heavy side will likely be exceeded and the trailer will not handle correctly.
Never leave a jobsite or equipment yard without ensuring that the trailer's electrical cable is properly connected and all exterior lights and the electric brakes are working. "There is no real standard for the wiring," says Lancaster. "That is still a common problem." Look at the trailer and determine if the wiring is of acceptable quality. "Is it sealed? How do they fasten the wires and what kinds of lights do they use?"
There are also several different types of brake controllers. "They are all compatible with the trailer brake," Lancaster notes. "But some are solid state, where you manually adjust the gain. It is always important to pay attention to that."
Sometimes, a driver towing a heavy load will turn up the gain. Once the load is delivered and the driver prepares to leave, he taps the brakes and the trailer locks up, so he turns the gain down. When he returns for another load, he forgets to turn the gain back up. "He doesn't necessarily have enough brakes. Adjusting the brakes is known as synchronization. You need to synchronize your brakes every time you use them," says Lancaster.
Finally, make sure your trailer tires are up to the task. A visual check is not enough. Trailer tires may be worn out even if they have plenty of tread left. Sitting for extended periods of time or carrying excessive loads shortens tire life.
According to TISC, statistics show the average life of a trailer tire is about five years under normal use and maintenance conditions. After three years, consider replacing the trailer tires with new ones, even if the tires have adequate tread depth. As is the case with most vehicle tires, improper inflation is the main cause of failure.
"The type of tires designates your travel speed," says Lancaster. Most trailer tires are a Special Trailer (ST) version. "ST tires don't have a speed rating like normal passenger car and truck tires. The trailer owner's manual should tell you the proper speed [at which] those tires can be used.
"Every time you come to a stop or every time you get out of your vehicle, walk around the trailer," he advises. "There are many dynamics and things can come loose. Check the safety chain. Check the coupler. Check to make sure the bolts are good in the hangers - it is fairly easy to see. Check your cargo straps. It needs to be a habit."