An overweight motorhome is an overworked motorhome.
By Jim Brightly, F358406
February 2011
A motorhome is a wonderful tool. It can take you to places you might not ever visit if you weren’t an RVer. It can be enhanced with accessories to make using it even more enjoyable. But like any tool, a motorhome can be overstressed if you ask it to do more than it was designed to do.
Perhaps the most common example of overstressing a motorhome is overloading. When you overload a motorhome, the extreme weight can cause axle bearings to fail prematurely; shorten tire life; allow unsafe swaying in crosswinds or on curves; increase driver fatigue; and cause the suspension to sag by putting undue wear on its components.
As you probably have read or heard, the first thing you need to do before purchasing any new or used motorhome is to weigh it. You certainly don’t want to purchase a vehicle that doesn’t have the cargo-carrying capacity that you will require. After you buy a motorhome, continue to weigh it at least once a year. Your motorhome’s weight can be a major factor in the duration of its service life.
When loading your motorhome, you must think about proper weight distribution. Consider the locations of its appliances and holding tanks when you’re filling the cabinets and storage compartments. Use this knowledge to properly distribute the movable cargo weight from side to side and from front to back. The idea is to balance the weight throughout the motohome and not to overload a particular axle or wheel position. In addition, items should be placed in such a fashion that they won’t shift during travel. Improper weight distribution and heavy items shifting while you are driving can have an unfavorable effect on the motorhome’s handling, ride quality, and braking capability.
That’s why it’s imperative that you know the weight ratings for your motorhome and understand how to use these numbers when you weigh the vehicle. The process can be confusing, particularly for new owners or those who don’t weigh their vehicle on a regular basis. We’ll start by explaining where to find the various weight ratings for your motorhome, what they mean, and how to use them once your motorhome is weighed.
Understanding Weight Ratings
Every vehicle manufactured in the United States for highway use is required to have a Federal Motor Vehicle Safety Compliance (FVSC) label on a wall next to the driver’s seat. This label must include the vehicle identification number (VIN); the gross vehicle weight rating (GVWR); the gross axle weight rating (GAWR) for both the front and rear axles; tire size and rim size information; and air pressure recommendations for the specific tires. Many motorhome manufacturers also include the gross combination weight rating (GCWR) for owners who intend to tow a car or trailer behind the motorhome, but this is not required. On motorhomes there may be two of these labels: one affixed by the chassis manufacturer for the incomplete vehicle; and one affixed by the motorhome manufacturer with the final weights for the finished vehicle.
Prior to June 2, 2008, motorhome manufacturers that were members of Recreation Vehicle Industry Association (RVIA) “” and some companies that were not members “”posted additional weight information on the label, such as the unloaded vehicle weight (UVW), cargo carrying capacity (CCC), and sleeping capacity weight rating (SCWR).
However, since June 2, 2008, the federal government has mandated that all motorhomes include an occupant and cargo carrying capacity (OCCC) label in addition to the FVSC label. Besides the VIN, the OCCC label provides the maximum combined weight of occupants and cargo that should never be exceeded; the number of safety belt-equipped seating positions; and a statement that provides information as to the weight of a full load of water in the motorhome and a reminder that the tongue weight of any towed trailer or vehicle counts as cargo. This label can be permanently affixed next to the FVSC label with a temporary copy on the inside of the entrance door referencing the permanent location, or the permanent label can be affixed at the entry door only. The addition of this label supersedes the previous RVIA label; therefore, the RVIA label is no longer required of manufacturer members.
Weight Rating Definitions
Below are definitions from the Recreation Vehicle Safety & Education Foundation (RVSEF) for the various weight ratings you may find posted for your motorhome. Become familiar with these definitions so you can more accurately determine whether your motorhome is within the safety margins set forth for your vehicle.
Gross vehicle weight rating (GVWR) is the maximum allowable weight of the fully loaded vehicle, including liquids, passengers, cargo, and the tongue weight of any towed vehicle.
Gross axle weight rating (GAWR) is the maximum allowable weight each axle assembly can carry, as measured at the tires, therefore including the weight of the axle assembly itself. This rating is established by considering the rating of each of its components (tires, wheels, springs, and axle) and rating the axle on its weakest link. The GAWR assumes that the load is equal on each side.
Gross combination weight rating (GCWR) is the maximum allowable combined weight of the motorhome and the attached towed vehicle. The GCWR, a term borrowed from the trucking industry, assumes that both vehicles have functioning brakes. Check your vehicle owners manual or chassis guide for information about supplemental braking requirements.
Unloaded vehicle weight (UVW) is the weight of the motorhome as built at the factory with full fuel, engine oil, and coolants. The UVW does not include cargo, fresh water, LP gas, occupants, or dealer-installed accessories. (This figure is no longer used but may appear on motorhomes built prior to June 2008.)
Sleeping capacity weight rating (SCWR) is calculated by multiplying the manufacturer’s designated number of sleeping positions by 154 pounds. (This figure is no longer used but may appear on motorhomes built prior to June 2008.)
Cargo carrying capacity (CCC) is equal to the GVWR minus the UVW, fresh water weight (including the water heater), full LP gas weight, and the SCWR. (This figure is no longer used but may appear on motorhomes built prior to June 2008.)
Occupant and cargo carrying capacity (OCCC) is equal to the GVWR minus full LP-gas weight. (This figure does not appear on motorhomes built prior to June 2008.)
As you can see, the CCC that was used prior to June 2, 2008, took into account the added weight of the fresh water tank as well as the weight of passengers (as found in SCWR). The new federal OCCC number does not factor in water and passenger weights but instead considers them part of the overall cargo weight. The new OCCC label shows the maximum combined weight of occupants and cargo, the weight of the fresh water, and the number of seating positions that have seat belts.
To assure that a customer buying a new motorhome gets a useful and authentic OCCC number, the new federal regulation also requires that a dealer provide an updated weight label if more than 100 pounds in dealer-installed accessories (an awning, another air-conditioning unit, a spare tire, etc.) are added to the factory weight while the motorhome is on the dealer’s lot.
Weighing The Motorhome
It is the owner’s responsibility to know the loaded weight of the motorhome and the combination weight of the motorhome and towable, if applicable. The only way to find this information is to have the motorhome weighed. But getting the correct weights necessary to make an educated conclusion as to whether the motorhome is within its safety margins isn’t as simple as rolling the vehicle onto a scale to find the total weight of the vehicle. More detailed measurements are needed.
That’s why RVSEF recommends having the motorhome weighed not only for gross vehicle weight and axle weights but for weights at all four corners of the motorhome. Just because a motorhome’s weights fall within the GVWR and GAWR parameters set forth by the manufacturer does not mean that one or more areas might be overloaded. By obtaining precise measurements at all four wheel positions, it is possible to determine whether the load on an individual axle is balanced and that one side is not heavier than another. RVSEF provides four-corner, wheel-by-wheel weighing service at FMCA conventions and other RV events. After the weighing procedure, owners receive a detailed report from RVSEF that the owner can use to redistribute cargo should one corner be significantly heavier than the other, and to help determine the pressures to which the tires should be inflated. During FMCA conventions, FMCA subsidizes the cost of the RVSEF weighing service so that members can receive $15 off the fee.
Although RVSEF’s weighing service will provide the most complete measurements for determining weight distribution and tire inflation, you may not be in locations where the service is available. If that’s the case, you should still have the motorhome weighed at least once a year to make sure all of the cargo additions you’ve made throughout the past year have not radically impacted the weight of the motorhome.
Most truck stops have scales where you can get the motorhome weighed. You also can look in the Yellow Pages for “Scales, Public” for a public scale. Scales also can be found at many public dump sites, moving companies, recycling facilities, etc. When getting your motorhome weighed at one of these scales, ask for three weights: front axle, total, and rear axle. If the scale can’t give you individual axle weights, you’ll have to have them weighed separately. To do this, pull the coach onto the scale and stop with just the front wheels on the scale. Now, move forward until both axles “” or all three if you have a motorhome equipped with a tag axle “” are on the scale, and stop. Finally, pull forward until just the rear axle(s) is still on the scale and stop. Don’t worry if the separate axle weights don’t add up precisely to the total weight “” you’d have to know exactly where your motorhome’s fore-and-aft balance point is for these to match exactly.
The motorhome’s actual GVW should be determined with the motorhome fully loaded, including fuel, LP gas, water, personal items, and the normal number of people and pets usually carried. The gross weight shouldn’t exceed the GVWR determined for the vehicle by the manufacturer, and likewise the weight of each axle (front and rear) should not exceed the corresponding GAWR. Should these weights exceed the limits listed on the FVSC label, the motorhome will show accelerated wear on all driveline components (tires, axle bearings, suspension, steering, etc.), not to mention the added risk to your family’s personal safety.
Use the accompanying worksheet “” or create your own “” to help you determine whether your vehicle’s weights are in accordance with the ratings listed on the FVSC and OCCC (or RVIA) labels. Copy the figures from the data labels affixed to your motorhome into the second column. Then enter the actual weight figures in the first column and subtract to find the differences. If the actual weight per axle is higher than the label figure, that axle is overloaded. If the total weight is higher than the label figure, your vehicle is overloaded. If the combined weight is higher than the label’s GCWR, the motorhome and towable together weigh more than the vehicle was designed to pull.
RV WEIGHT INFORMATION WORKSHEET
Actual Weight Data Label Information
Front GAW: Front GAWR:
Rear GAW: Rear GAWR:
GAW (tag): GAWR (tag):
Total GVW: GVWR:
LPG: LPG:
UVW: UVWR:
OCCC: OCCC:
GCWR*: GCWR*:
*Total including towable
If you would like more information about RV weight and tires, you should consider attending the applicable seminars at FMCA conventions and rallies, or you can request a copy of the RV Safety & Education Foundation (RVSEF) RV Safety Training Program, which includes information about Towing, Personal Safety, Weight, Tires, Propane, Fire, Driving, Electrical, and Motor Fuels, and includes an excellent video as well. Send a check for $24.95, plus $5.95 for shipping and handling (Canadian shipping is $6.95 USD) to RV Safety & Education Foundation, 4575 Annette Ct., Merritt Island, FL 32953. For more information, call (321) 453-7673 or visit www.rvsafety.com.