Weight plays a huge role in the world of RVs. Exceed weight in any area, and you compromise not only equipment and performance, but also safety. Here are a few weight terms and guidelines that you should understand to enjoy safe and trouble-free RV adventures.
Basic Weight Terms
Also referred to as gross actual weight or load; it’s the amount in pounds or kilograms that a motorhome, tow vehicle (truck, sedan, SUV, motorhome), towable (travel trailer, camping trailer, fifth wheel, toy hauler), or toad (motorized vehicle towed behind a motorhome) weighs when placed on a scale. Actual weight also applies to individual RV components like axles, tires, trailer tongues/hitch pins, hitches, etc. Actual weight changes as fluids, passengers, cargo, and gear are added, removed, or redistributed.
Weight rating is the maximum amount of weight a vehicle, towable, or individual RV component has been engineered to handle. Weight ratings are determined by manufacturers, and you must consider them sacred.
The gross weight of an RV is directly affected by the amount of fuel and fluids it carries. And different fluids have different weights associated with them: water weighs 8.3 pounds per gallon, gasoline 5.6 ppg, diesel fuel 6.8 ppg, and propane 4.2 ppg. So, if your motorhome fuel tank holds 100 gallons of gasoline when filled, this by itself will add 560 pounds to the coach. Fill a 50-gallon freshwater tank, and the water itself weighs 415 pounds.
General Weight-Rating Terms
Gross Vehicle Weight Rating (GVWR):
the maximum allowable weight of a tow vehicle or a towable when fully loaded (including fluids, fuel, passengers, and cargo). For a towable this is also referred to as gross trailer weight rating (GTWR).
Gross Combined Weight Rating (GCWR): the maximum combined weight that the tow vehicle and a towable can weigh when hitched together and placed on a scale.
Gross Axle Weight Rating (GAWR):
the most that an individual axle can weigh when a tow vehicle or towable is loaded. Note that even if an actual axle weight falls within the GAWR, you need to measure individual wheel weights. One of the wheels might exceed half the GAWR of the axle, and you need to ensure that the actual axle weight is balanced between each of its wheels. Also, if a motorhome has a tag axle, the unit will have three individual GAWRs (one for each axle).
Gross Tire Weight Rating:
the maximum weight rating a tire can carry at a specific inflation pressure. These ratings are found on the side of each tire, which is also where you can sometimes find recommended towing speeds.
Hitch-Weight Rating Terms
the maximum load that a tow-vehicle manufacturer has determined can be added off the back of the tow vehicle by the trailer tongue and hitch device when they’re coupled to the tow vehicle’s hitch ball. To improve road performance, you can use a weight-distribution device (hitch) to shift the weight forward to the front axle of the tow vehicle and aft to the axle(s) of the towable. However, you need to check with your manufacturer to be sure that your tow vehicle can safely use a weight-distribution hitch. And you should never use a weight-distribution hitch to offset an over-the-limit hitch weight. The only safe way to do this is to redistribute the cargo or start unloading and get that weight down!
For fifth-wheel and goose-neck trailers, the hitch-weight rating is the maximum amount that can be added inside the bed of a truck (directly above the rear axle) when the kingpin on the towable is latched in place by the jaws of the hitch.
A travel trailer can have a receiver-type hitch attached to the back of the chassis where you can attach a cargo carrier (for motorcycles, say). Ask the manufacturer for the weight rating of this hitch and the gross amount of weight that the travel trailer chassis is designed to carry off the back. Note that loading a cargo carrier will reduce the hitch weight; you might need to redistribute the cargo in the trailer to ensure that the weight at the hitch stays within 10% to 12% of the actual weight of the trailer.
Trailer Tongue/Hitch-Pin Weight:
The front of a towable chassis that’s coupled with the tow vehicle’s hitch ball is called the tongue. The hitch pin/kingpin is on the underside of the landing at the front of a fifth-wheel or goose-neck chassis. It’s attached inside the truck bed via jaws on a hitch that’s mounted over the rear axle. The guidelines for maximum loads that the tongue or hitch pin/kingpin can add to their hitches as prescribed by the RV Industry are as follows:
Trailers with GTWR of less than 2,000 pounds need to have an actual tongue weight that equals 10% of the GTWR.
Trailers with GTWRs above 2,000 pounds need the tongue weight to fall between 10% and 12% of the GTWR.
Fifth-wheel and goose-neck hitch pin weights needs to fall between 15% and 25% of the GTWR.
Tongue/Pin Weight Rating:
the maximum amount of weight or load that a hitch manufacturer has determined that its hitch can accept from the tongue on a trailer or the kingpin on a fifth wheel.