Every RV has various weight ratings. The purpose of this article is to familiarize the RV'er with the various weight definitions and weight ratings. It is VERY important that every RV'er become familiar with their vehicle, hitch, and tire ratings. Exceeding any of these ratings may result in potential damage, a potential safety issue, voidance of your vehicle's warranty, potential voidance of your insurance policy, and may even be a violation of law in some states.
Everyone is strongly urged to have their RV weighed at each individual wheel. Just knowing your total RV's weight, or even the weight on each axle, is not sufficient. It is very possible that one tire on an axle is overloaded while the axle itself is within its weight rating.
All of the ratings discussed below can either be found on the RVIA sticker located inside your vehicle, except for the tire ratings which are found on your tires.
GVWR: Gross Vehicle Weight Rating. The maximum allowable weight of the fully loaded vehicle, including all liquids, passengers, cargo and the tongue weight of any towed vehicle. (NOTE: a vehicle that is towed "four wheels down" behind a motorhome does not have any tongue weight.)
GAWR: Gross Axle Weight Rating. The maximum allowable weight each axle assembly is designed to carry. To determine that maximum weight on each tire, divide the GAWR by 2. As an example, if your front GAWR is 9,000 lbs, then the maximum weight on each tire is 4,500 lbs.
GCWR: Gross Combination Weight Rating. The maximum allowable combined weight of the tow vehicle and the attached towed vehicle. GCWR assumes that both vehicles have functioning brakes. Specifically for Discovery motorhomes, the hitch is rated to tow 5,000 lbs. Therfor, the GCWR is 5,000 + the GVWR. Freightliner advised it is possible to tow up to 10,000 pounds with an appropriate hitch.
GTWR: Gross Trailer Weight Rating. The maximum allowable towed vehicle weight.
TWR / TLR / VLR: Tongue Weight, Tongue Load and Vertical Load Ratings. Various terms for the maximun vertical load that can be carried by the hitch.
The maximum load that a tire can carry is engraved on the sidewall along with a corresponding COLD inflation pressure. There are also some additional important items, depending on whether the tire is a truck tire or a passenger car tire. NOTE - you MUST always set your tire pressures when the tire is COLD. This means that the tire has set idle for at least four hours, and ideally is not in direct sunlight.
For a TRUCK tire, as an example, you may find something like 5,000 lbs (single), 4,500 lbs (dual) at 100 psi. Tire weight ratings are different for single or "dualie" applications. Duals applications have derated load-carrying capacities due primarily to less heat dissipation caused by the two tires in close proximity. However, for truck tires, the tire inflation pressure is the MINIMUM inflation pressure required to carry the MAXIMUM load. Also, the maximum load is specified at either 55 mph or 65 mph (consult your tire manufacturer's chart). If you intend to drive over this speed, the chart will also tell you the maximum speed and the inflation requirements for this maximum speed.
For a PASSENGER CAR tire, as an example, you may find something like 2000 lbs at 35 psi. In this case, 35 psi is the absolute maximum tire pressure for that tire. Also, passenger car tires are "speed rated", such as H, V, Z which is part of the tire designation. Care must be taken to not exceed the speed rating for your tire.
UVW: Unloaded Vehicle Weight. The weight of a vehicle as built at the factory with full fuel, lubricants and coolants for engine and generator. It does NOT include any cargo, passengers, fresh water. LP or any dealer-installed accessories.
NCC: Net Carrying Capacity. The maximum weight of all passengers and cargo (personal belongings, food, fresh water, LP, dealer-installed accessories, etc) that can be carried by an RV. This is the older 1996 RVIA definition and has been superceded in 2000 by CCC (see below).
SCWR: Sleeping Capacity Weight Rating. The manufacturer's designated number of sleeping positions multiplied by 154 pounds.
CCC: Cargo Carrying Capacity. This is the new 2000 RVIA definition and is equal to the GVWR minus the weight of ALL of the following: UVW, full fresh potable water including water heater, full LP gas and SCWR.
None of the above tell you WHERE you can carry passengers and cargo. One axle - or one tire - can be easily overloaded when you add passengers and cargo. A'WEIGH We Go reports that over 60% of all the RV's they weigh are overloaded at either an axle or a tire.
Also, vehicle weights provided by the manufacturer's are "estimates". In the interests of safety, have your vehicle weighed properly for each tire. If you are considering the purchase of any RV, have it weighed by wheel before you pay for it! There are many very expensive RV's (diesel pushers included) that have very little CCC on an axle, much less by tire.
If you weigh the RV without full fluids, you can estimate the load by noting the location of the fluid and calculating its weight. Pounds per gallon of common liquids: Diesel - 6.6, Gasoline - 6.0, Water - 8.3, LP - 4.2.
Also, keep in mind that the average full-timer carries over 3,000 pounds of "stuff". The average vacationer carries over 2,000 pounds of "stuff".
The DISCOVERY OWNERS ASSOCIATION, INC, was formed to promote the sharing of information and the camraderie of fellow Discovery motorhome owners. Membership in the club is limited to owners of Fleetwood Discovery motorhomes.