The weight of your RV is critically important. Weight affects your safety and the safety of others on the road plus the economy and operation of your RV. Weight is also regulated—that is, you must comply with the law wherever you might be driving.
While it is impossible to be too underweight, it is dangerous and illegal to be overweight. Additionally, all this weight rides on your tires. Therefore, your tires are of the utmost importance since they are the single point of contact between your motorhome (or your towable) and the highway at all speeds. Take good care of your tires. Simply put, if you don’t, it will cost you money and may hurt you physically.
Learning How Much Weight You Can Carry
All recent RVs must have a label showing the weight capacity of the rig in both empty (unloaded) and maximum weight configurations. This labeling complies with the Recreational Vehicle Industry Association (RVIA) and/or the Federal Government Standards. Locate your label and become familiar with the information. It is often found on the inside of a cabinet or closet and is usually the size of a normal sheet of paper.
The abbreviations used on the label are fully explained. It is important to recognize that these labels show the estimated carrying capacity of this RV. If the RV was manufactured prior to September 2000, the term Net Carrying Capacity (NCC) was used. NCC is the difference between Gross Vehicle Weight Rating (GVWR) and the Unloaded Vehicle Weight (UVW) and does not consider the weight of the water, propane, or people you might be carrying. You, the owner, have to remember to factor all this in. Without this weight calculated in, the NCC looked great—that is, an RV seemed to be able to carry lots of stuff.
In September 2000, the RVIA adopted a new term called Cargo Carrying Capacity (CCC) and in the broadest definition, the CCC is the difference between Gross Vehicle Weight Rating (GVWR) and the Unloaded Vehicle Weight (UVW). The UVW is the weight of the basic unit at the factory and included a full fuel tank, all coolants, and engine oil.
However, that is just a starting place from which you must calculate your actual CCC. Starting with the GVWR , first subtract the UVW, then subtract the weight of a full tank of water including water heater capacity, a full tank of propane, and the hypothetical weight of passengers—known as the Sleeping Capacity Weight Rating (SCWR).
The SCWR is determined by multiplying 154 pounds (70 kilograms) times the number of sleeping positions (not the number of people actually using the RV and not their actual weight).
At this point in your calculations, you have determined some remaining “unused” weight and you are getting close to the final Cargo Carrying Capacity for a particular RV. But, as they say, “Wait, there’s more.”
The CCC does not account for any accessories added to your RV after it was manufactured. The weight of accessories (satellite dish, solar panels, etc.) must also be subtracted from the your working CCC figure.
Now, Your Personal Stuff
Your particular calculated number—a weight given in pounds—is your actual CCC and is the total amount of personal “stuff” you can safely and legally carry before exceeding the manufacturer’s Gross Vehicle Weight Rating (GVWR). This includes the array of things such as canned goods, ladder, lawn chairs, pots and pans, clothing, the dog, tools, cleaning supplies, books, dishes, and the coffee pot, to name just a few.
The CCC directly affects the amount (in weight) of the personal items you can carry. Prior to the purchase of any RV (new or used), you need to know the CCC.
I realize it is extremely difficult to know or even estimate the weight of your personal stuff especially if you are new to RVing. However, you can calculate the CCC for any RV and knowing this will at least give you a starting point. If your calculated CCC turns out to be somewhat small, when your stuff is loaded, that great looking RV you are planning to buy may actually be illegal (overweight) on the road. Interestingly, this may not be a problem in the operation of the RV but definitely could be a problem if your overweight vehicle is in an accident. The total weight of the RV must not exceed its GVWR nor should any axle exceed its particular weight rating—that is the law in every state and all the Canadian provinces.
[Author note… It is possible to have a full tank of fresh water plus full grey and black tanks, too. For example, if you are in a campground with water but not hooked up to sewer, you could have a full fresh water tank and full grey and black tanks, too.
On my motorhome, the grey and black tanks are 56-gallons each. If these were full (let’s round them down to 50-gallons each), I would have 100 gallons of extra liquid weighing at least 8.35 pounds per gallon. That would be an extra weight of 835+ pounds! If my personal stuff weighed close to my accurately calculated CCC, all of a sudden, I would be overweight due to those full grey and black tanks.]
Why is This Important?
Load your RV as you would for normal travel. Locate a public weigh-scale (most commonly found at truck stops). Have your RV and toad, or your tow vehicle and trailer weighed axle-by-axle. Drive and steer axles can be weighed separately on any normal scale. However, it is not unusual for one side of an axle to have more weight than another. Weighing by axle will not reveal any side-to-side imbalence.
Ideally, it is best to have your RV weighed at each independent wheel position to determine how much remaining capacity you may have and where it is located. However, locating facilities to weigh each wheel position is more difficult. Occasionally, you can move slightly off a truck scale in such a way that you can obtain individual wheel weights. More often, this service is provided at RV rallies and shows and the
weighing may be part of a safety seminar. There are private companies providing weighing services at these events and in campgrounds as well. All will physically weigh your coach or trailer by individual wheel-position.
Once you know the weight on each tire position, you can easily determine if you exceed any specification—tire pressure, axle, or vehicle—and make adjustments accordingly.