RV engineer spills the dirty truth about RV cargo capacity

By Andrew Herrick, The RV Engineer
In the alphabet soup of RV towing capacities, Cargo Carrying Capacity (CCC) is usually overshadowed by Gross Vehicle Weight Rating (GVWR), Gross Combined Weight Rating (GCWR), Gross Axle Weight Rating (GAWR) …

All right, I’ll stop! No sense in shoving alphabet soup down your throat until you vomit it back up. But you should really know more about your RV cargo capacity, because …

“But, Andrew,” you interrupt, “that’s techno-talk. That’s for RV nerds (no offense). I’m just shopping around!”

Then you are EXACTLY who should be reading this post! Most buyers don’t pay attention to that little black-and-yellow sticker until AFTER their purchase, and by then it’s $75,000 too late.

What is RV cargo weight and how is it calculated?

RV cargo weight is how much “stuff” you can add before overloading the RV.

Calculating cargo capacity is governed by the FMVSS 110 and FMVSS 120 standards.

The simple equation is: CCC = GVWR – UVW

• Where GVWR = Gross Vehicle Weight Rating, or the maximum scale weight of a fully loaded RV.
• Where UVW = Unloaded (or Unladen) Vehicle Weight, which is the weight of the RV, plus operating fluids, as configured for delivery to the dealership. This will include forced options as well.

PUBLIC SERVICE ANNOUNCEMENT: A lot of the other so-called “RV blogs” are WRONG about Cargo Carrying Capacity! They’ll share an equation that’s been obsolete since 2008. Today, water, occupants and stuff are all considered “cargo,” and you’re responsible for tracking their weight.

Sounds simple, right? Well … there is a lot of fine print.

RV cargo capacity: What you need to know!

Let me do my part to clean up some of the myths and misconceptions about RV cargo weight capacities. Here are four things you should know:

1. Cargo labels are accurate to within ~100 lbs.

Dealers are allowed to add up to 100 lbs. or 1.5% of the GVWR (whichever is less) to the RV without replacing or correcting the CCC label.

This is because dealers commonly add batteries and small accessories to the RV. Because tires are not sensitive to very small overloads, NHTSA has allowed dealers to add accessories without the hassle of swapping stickers.

2. Propane and fuel are included in the base weight

The UVW includes the weight of full propane and fuel tanks.

That’s good news! In other words, the law assumes that propane is as critical to your RV as gasoline is to a car. So the weight of that propane is built into the base weight; you don’t need to track it separately.

Same thing with fuel: Gasoline and diesel are already included in the unladen weight.

3. Water and occupants are considered payload

… But water and occupants are treated as cargo.

This is why all RVs have a sticker explaining that water weighs 8.3 lbs. per gallon. That information helps you estimate the remaining cargo capacity after filling your freshwater tank (and don’t forget the water heater tank!).

^Now, this rule causes lots of confusion. Let’s see how the math plays out:

Example: If your RV has, say, 1,000 lbs. of cargo capacity, what’s left after filling your water tank (6 gallons) and freshwater tank (30 gallons)? We’ll ignore the water in the supply lines.

Eq: 1,000 – (6+30)*8.3 = 701 lbs.

So you’ve reduced your payload capacity by 300 lbs. just by filling up your tank! And if you were also carrying 15 gallons of black water and 20 gallons of gray water to the nearest dump site, you would only have 410 lbs. of payload left. Yikes!

4. The CCC sticker is law!

The CCC sticker isn’t just there for legal reasons.

As Tony Barthel shared in his post about dangerously overweight RVs, some salespeople told him that “the chassis are designed for much more than the sticker says.”

That is grossly inaccurate, deceptive, and dangerous. In my experience, RV manufacturers aren’t in the habit of arbitrarily knocking down capacities just to play it safe. We’re trying to make use of every pound we can!

And why does the salesperson think he can decide what the “real” cargo capacity is? Did he specify the axles? Did he calculate the tire reserve capacity? And did he run an FEA stress analysis on the frame? No??? I didn’t think so!

The dirty truth about RV cargo capacity

Here’s an unfortunate truth: CCC stickers don’t sell RVs. Cabinets do. People are like honeybees: We love to see little pockets full of goods and goodies.

So when you walk into a rig, what’s the first thing that catches your eye? Cabinets, cabinets, cabinets! The hidden sliding drawer beneath the dinette, the overhead cargo netting above the bed, the cavern beneath the master bed. And we haven’t even talked about the pass-through basement garage, the bike rack, the 300 lb. rear hitch…

But did you know that just filling your cabinets and storage spaces could overload your RV? 

Here’s what Forest River says:

Did you catch that? “You cannot necessarily use all available space when loading your unit.” Not unless most of your luggage is down comforters and bags of marshmallows, that is.

I would humbly argue that a significant number of RVs are built with inadequate RV cargo capacity. I think the problem is worst on:

• Travel trailers longer than 30 feet
• Extended Class C motorhomes, especially those on a 12k or 14.5k chassis
• Gasoline-powered, front-engine Class A motorhomes
• Any “ultralight” camper with 2+ slide-outs

But don’t lynch the manufacturer just yet! Yes, it’s easy to blame the builder—and they certainly are culpable. I’m not denying that. But when the customer keeps begging for higher towing capacities, for more slide-outs, for tile floors and dual air conditioners and not an inch of wasted space, then don’t be surprised when you get what you asked for. Et tu.

What’s a good cargo carrying capacity for an RV?

Pounds are like potato chips: One doesn’t seem like much, but when one follows the other… Wait, where did the bag go?

Just remember how difficult it is to shrink your luggage to 40 lbs. for a checked bag on a plane!

I recommend at least 1,700 lbs. cargo capacity or 500 lbs. per person, whichever is greater. This is the minimum—more is better!

• If you’re a full-timer, add 50%.
• If you’re a boondocker or adventurer, add 25%.
• If you plan on towing a second vehicle with your motorhome, add the tongue weight of the toad, dinghy or car hauler.
• If you have a toy hauler, the weight of the toys should be added separately.

For some other back-of-the-envelope math, I’ve created the following graduated scale, where the minimum CCC should be:

• 25% of the GVWR for RVs below 10,000 lbs.
• 20% of the GVWR for RVs between 10,001 lbs. and 19,999 lbs.
• 15% of the GVWR for RVS above 20,000 lbs.

To my knowledge, there is no minimum CCC legal regulation. So long as the RV manufacturer has met the tire loading requirements, CCC is left to their discretion.

I would not purchase an RV with a payload capacity of 1,000 lbs. or less unless it was a mini travel trailer (e.g., Scamp) or teardrop trailer.

Big takeaways for the RV owner

I’ve thrown a lot at you in the past 1,200 words. Here are the big takeaways:

1. Don’t assume your RV can carry what you think it can based on storage space.
2. Extended Class C’s, gasoline-powered Class A’s, and 30-ft.-plus travel trailers are the usual suspects.
3. Get the cargo capacity from the CCC sticker, not the salesperson.
4. Remember that occupants and water will count against cargo.
5. Plan on 500 pounds per person plus extra for toys.
6. If the numbers don’t add up, keep shopping.
7. Weigh your RV after loading to double-check your estimates!

More by Andrew Herrick.

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