The GCWR is the maximum allowable total loaded weight of the motorhome and towed vehicle combined. The GCWR and unbraked load capacity are specified by the chassis manufacturer.
The GCWR is not related to a motorhome's braking capability; it is based on the motorhome's ability to pull the towed vehicle. If the towed vehicle's weight is greater than the unbraked towing capacity of the motorhome chassis, a supplemental braking system should be considered. Some chassis manufacturers recommend that supplemental brakes be used when pulling towed vehicles that weigh as little as 1,000 pounds.
Towing too heavy of a vehicle can lead to a "tail wagging the dog" scenario. During an emergency lane change or a lane change on wet roadways, a heavy towed vehicle could push the rear of the motorhome sideways, creating unstable driving conditions and a dangerous situation for the occupants and others sharing the road.
Auxiliary braking equipment is designed to reduce stopping distance and stop the motorhome and towed vehicle more quickly. Myriad systems are available; their methods of activation varies but include air, surge, electric, hydraulic and inertia.
Some supplemental braking systems come with a breakaway system or offer one as optional equipment. This feature is designed to automatically stop the towed vehicle if it were to break away from the motorhome.
For more information about supplemental braking products, contact manufacturers and suppliers of supplemental braking systems. Family Motor Coaching magazine published a list and description of 20 supplemental braking products in its July 2003 issue.
Many states and Canadian provinces have braking requirements for trailers but do not specifically address towed vehicles. Contact local law enforcement authorities in the areas you will be traveling for information on current regulations.
Classes of towing equipment
There are four classes of towing equipment, rated according to the weight of the towed vehicle it is intended to be used with. The weights refer to the GVWR (maximum weight fully loaded) of the towed vehicle:
Class I: up to 2,000 pounds
Class II: 2,001 to 3,500 pounds
Class III: 3,501 to 5,000 pounds
Class IV: 5,001 to 10,000 pounds
Towing a car with a GVWR of 3,600 pounds requires using a tow bar, safety chains and a base plate that each have a Class III rating. Also, make sure the receiver on the back of the motorhome has a rating that is sufficient for towing your vehicle.