Friday, March 24, 2023


Why your RV’s GVWR is different than its GAWR

Alphabet soup is hard to choke down, I know. But if you can stomach the acronyms for a few minutes, I think you’ll learn something important about your RV’s weight capacity—and maybe save yourself a tire blowout along the way.

Today’s question: Why does your RV’s GVWR not match its GAWR? In other words, why is your RV allowed to weigh more or less than what the axles can carry alone? 

Definitions of GVWR and GAWR for RVs

As you probably know, Gross Vehicle Weight Rating (GVWR)also known as Gross Trailer Weight Rating (GTWR) for towables—is the maximum allowable weight of your RV with all cargo and passengers. This number is determined by the RV and/or chassis manufacturer. Your actual weight can never, ever exceed the GVWR. 

Example: Your 2023 Winnebago Travato 59G has a GVWR of 9,350 lbs. No matter what, your Travato plus all cargo and passengers can never weigh more than 9,350 lbs.

Helpful Hint: GVWR is also equal to Unloaded Vehicle Weight + Cargo Capacity. You can find the GVWR and GAWR on your VIN sticker, usually located on your driver’s door jamb or front exterior roadside wall. 

As you also probably know, Gross Axle Weight Rating (GAWR) is the maximum allowable weight placed on an axle, including all cargo and passengers. Each axle has its own GAWR. This is determined by the axle manufacturer, and it doesn’t include unsprung weight like tires and brakes.

Example: Your 2023 Winnebago Travato has two axles: a front and a rear. The front axle has a GAWR of 4,629 lbs. The rear axle has a GAWR of 5,291 lbs.

Helpful Hint: In motorhomes, the front axle’s GAWR is normally referred to as the FGAWR. The rear axle’s GAWR is the RGAWR. In travel trailers and 5th wheels with multiple axles, the multiple axles’ GAWRs can be summed into a Combined GAWR—as long as the axles are properly equalized!

Why RV GVWR is greater than GAWR?

If you’re quick at math, you probably noticed that the Travato’s GVWR of 9,350 lbs. is less than the sum of its axles: 4,629 + 5,291 = 9,920, not 9,350! What happened to the missing 570 lbs.?

Don’t be exiting the room if you have a travel trailer or 5th wheel. You probably have the opposite conundrum. Your GVWR is probably more than your combined GAWR, not less! (Unless you’re towing a triple-axle 5th wheel, in which case it’s probably less. Confused yet?)

Example: Check out this information from a dual-axle 2023 Brinkley 5th wheel (see below). Each axle has a 7,000 lb. GAWR, for a combined GAWR of 14,000 lbs. But, then why is the GVWR 14,495? Where did the extra 495 lbs. capacity come from?

It’s not magic. It’s math.

What Uncle Sam has to say about GVWR

Federal law restricts how GVWR should be calculated. Per CFR 49 571.120 and 571.110 in the FMVSS:

S9.1 On motor homes, the sum of the gross axle weight ratings (GAWR) of all axles on the vehicle must not be less than the gross vehicle weight rating (GVWR).

S9.2 On RV trailers, the sum of the GAWRs of all axles on the vehicle plus the vehicle manufacturer’s recommended tongue weight must not be less than the GVWR. 

Translation: For motorhomes, GVWR cannot be greater than the combined weight ratings of the axles! For trailers, however, GVWR can be greater than combined GAWR. That’s why RV GVWR is greater than GAWR.

So, if federal law allows the GVWR of a motorhome to be equal to the combined GAWR, why did Winnebago specify a smaller GVWR?

Well, I don’t work for Winnebago, so I don’t know. But it could be a number of reasons. The GVWR is the maximum allowable weight an RV can safely weigh. Maybe the brakes were maxed out at 9,350 lbs. instead of 9,920 lbs.? Maybe it was the strength of the chassis rails or the durability of the transmission? I haven’t a clue. But the limiting factor came before the GAWRs, whatever it was.

Next question: Why does the Brinkley 5th wheel get an extra 495 lbs. of GVWR?

Well, if you read the FMVSS regulation carefully, it says the GVWR can include the manufacturer’s recommended tongue weight. If we pause and think, this makes intuitive sense. The tongue weight of a camper is on the hitch or tongue jack, not the axles! So it doesn’t count toward GAWR.

But the code goes on to say this: “If tongue weight is specified as a range, the minimum value must be used.”

In other words, Uncle Sam will only allow RV manufacturers to use the most conservative estimate. As a rule of thumb, for travel trailers, we assume ranges of 10-15% tongue weight, and for 5th wheels, we usually assume 15-25%. So you’ll rarely see a GVWR greater than 110% GAWR for a travel trailer or 115% GAWR for a 5th wheel.

But again, if you’re quick at math, you probably noticed that 449 lbs. isn’t anywhere close to 15% of the total weight of the Brinkley fifth-wheel RV. Why did Brinkley err on the conservative side? Maybe they were concerned about the strength of the frame? Maybe they wanted to limit cargo capacity because of weight distribution? Again, I haven’t a clue. But the limiting factor came before the combined GAWR, whatever it was.

Key takeaways about GAWR

Now that you’re armed with all this new information about why RV GVWR is greater than GAWR, what should you do with it?

  • You can gut-check the factory numbers. For instance, if a 5th wheel manufacturer says GVWR is equal to 135% of GAWR, that should raise a red flag. That’s well outside of normal. 
  • You should double-check your side-to-side weight distribution. The math doesn’t check this for you. It’s not uncommon, particularly for motorhomes, to have one tire overloaded, even if you’re within your GVWR.
  • You should load your tongue correctly. If you underload your tongue, you could max out your axle capacity before your GVWR.
  • You should avoid traveling at your maximum GVWR because that may mean you’re also maxing out your axles. Leave yourself a buffer, if possible.

It’s also worth pointing that politics, not just engineering, may play a role. In some states, 3,000 lbs. GVWR is the cutoff for brake requirements, so many utility trailers are sold with a 2,990 lb. GVWR. Also, in some states, any trailer over 10,000 lb. GVWR requires additional taxes, regulations, or driver’s licensing. 



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Bob Walter
4 days ago

Great article! GVWR on a motorized vehicle is also significant with regard to braking ability.
GAWR does not account for braking, just weight capacity. Always stay within GVWR even if axles are spec’ed higher. The 2 are actually apples and oranges.

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