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RV engineer answers: Is maximum towing capacity just smoke and mirrors?

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You will almost never tow what you think you can. To those of you who have owned RVs for years, this isn’t breaking news. Some of you follow the 80% Rule of Thumb: Your “real-life” towing capacity is around 80% of the advertised maximum. But is that margin even sufficient?

Let’s get into the nitty-gritty. And if you remember nothing else, remember this: Payload capacity, not towing capacity, is the real limitation of your tow vehicle!

Getting an answer about towing capacity is really, really hard!

Reality or dream?

I’m an RV design engineer. That’s right—I design some of the RVs you all are towing right now! And while I love this industry, I agree with the thousands of customers who demand better service, better construction, and better quality control. And nowhere is that information gap more excruciating than when answering the question, “How much can I actually tow?”

In recent years, the National Highway Traffic Safety Administration (NHTSA) has revised several labeling requirements to make towing and cargo capacities less opaque. But most customers still have trouble swallowing the alphabet soup—and RV salespeople aren’t exactly handing out calculators!

So I’ll say it again:

Payload capacity and hitch weight—not advertised towing capacity—will usually limit what you can tow.

  • The cargo you add to your tow vehicle will drastically reduce what you can tow. In fact, with a full family and suitcases, you might not be able to tow anything!
  • Real-life tongue weights can easily slash your towing capacity by 20-50% compared to the advertised maximum.

It’s bad news, I know. And while the 80% margin rule is useful, it’s still woefully inadequate. But I’d rather you find out now than $50,000 later.

Can you even trust advertised towing capacities?

The advertised towing capacities of most consumer pickup trucks are governed by the SAE J2807 standard—

Hey, don’t doze off! Get back here!

Motor Trend shows how the SAE J2807 is actually a pretty amazing test. The Highway Gradeability test takes place on the 11.4-mile Davis Dam road, a nasty hill climb in the Arizona sandstone desert, where the outside temperature must be 100 degrees minimum. It’s literally hell on wheels. I have a hard copy at my desk, so I can promise you it’s serious business!

So towing capacities are (mostly) standardized across manufacturers. Vehicles must survive several eye-popping strength and endurance tests. So that’s the good news. You can reasonably trust that you’re comparing apples to apples, Ford to Chevy.

But … can that Ford F-250 really tow 20,000 lbs.? Like, really?

When it comes to towing, the devil’s in the details

Auto manufacturers have dreams about the coveted status of “best towing capacity in class!” They’ll squeeze every pound possible out of their pickups (and their brochures). Their job depends on it.

So yes, some half-ton pickup trucks can tow 13,000 lbs.—with the right engine, axle ratio, bed length, cab style, hitch, tires, towing package, tongue weight, and a full harvest moon.

That’s a lot of assumptions. Here are some of the calculation assumptions typically made. (Check your manufacturer’s Towing & Trailering guide for the most up-to-date information.)

  • Tow vehicle includes a 150-lb. driver and a 150-lb. passenger. (I don’t know about you, but I haven’t been 150 pounds since I was 16!)
  • Tow vehicle includes the factory-installed heavy-duty towing package.
  • No driving at high altitudes.
  • No cargo besides operating fluids.
  • No dealer-installed options or accessories.
  • RV is towed with a weight-distribution hitch, not a weight-carrying hitch.
  • RV has minimum allowable tongue weight (usually 10% for travel trailer or 15% for 5th wheel).

If any of those are not true … then you won’t be able to tow the maximum towing capacity. And in all my life, I’ve never met anyone who towed with a perfectly balanced hitch, no kids, no cargo, and no accessories! What a boring vacation that would be!

Let’s see how these real-life constraints change the maximum towing capacity for an RV.

P.S. You can find your advertised towing capacity on a Trailering Guide or Towing Selector chart from your manufacturer. You can also subtract your tow vehicle’s GVWR from its GCWR, both of which you can find on your Safety Compliance Certification Label.



What difference will just one pound of cargo make?

Adding cargo to your tow vehicle will multiplicatively reduce its towing capacity.

^That’s a super important sentence, so I recommend you read it again. You may not think that 90 pounds of cargo is a big deal. I mean, that’s just a large dog, right?

Let’s see what happens if you bring Fido along.

(Not Fido. Doesn’t weigh 90 lbs.)

If your advertised maximum conventional towing capacity is 13,000 lbs., then I’d wager my retirement account (not worth much these days) that the auto manufacturer is assuming 10% tongue weight and a weight-distribution hitch.

If Fido is sitting in the middle rear seat, let’s assume half his weight (45 lbs.) is on the rear axle.

Now, the physics of weight-distribution hitches (WDH) can get complicated, so we’ll skip the algebra. But if your WDH is set up with ~66% FALR (front axle load restoration), then roughly 1 lb. gained on the rear axle = 12 lbs. loss of towing capacity. (That’s a super rough estimate, but it makes the numbers easy.)

Translation: If we assume half the cargo weight is on the rear axle, then every 1 lb. of cargo = 6 lbs. loss of towing capacity. At a certain threshold, it shuts down towing capacity completely.

So 90-lb. Fido just removed 540 lb.s of towing capacity. (Bad dog!)

And once you add your two 50-lb. suitcases and another 100 lbs. of emergency tools, snacks, drinks, and fishing gear, you’ve lost another 1,200 lbs.! Oof.

Note that you’re still well underneath your GCWR. But that doesn’t matter. You can’t overload your tow vehicle’s rear axle—and that’s what usually gives way first with heavy towable campers!

What difference will just 1% of tongue weight make?

Again, I’ll eat my hat if the auto manufacturer isn’t assuming 10% tongue weight for travel trailers (or 15% for 5th wheels). So a “13,000-lb. towing capacity” is just another way of saying a 1,300-lb. maximum hitch weight.

So, what if your travel trailer actually has a 13.5% tongue weight? (Which is a very reasonable number within the usual 10-15% range).

Turns out, that’s an extra 455 lbs. on the hitch. Not good. And because tongue weight multiplies weight on the rear axle, you’ve probably overloaded your rear axle by even more, up to 500-700 lbs.

Yikes. So with a 13,000-lb. trailer, you’ve way, way overloaded your rear axle and tires. You’re risking tire blowouts and permanent suspension damage.

You’ll need an Atlas to hold up this tongue weight!

Once you crunch the numbers … with a 13.5% tongue weight, you could only tow 9,630 lbs., tops. Not 13,000. That’s 3,370 lbs. less than you thought!

(And we haven’t even added Fido yet.)

This is also why very few half-ton pickup trucks can reasonably tow a 5th wheel camper. The pin weight is just too much for the rear axle, especially once you climb above 15%!

So what’s a math-averse RV owner to do about towing capacity for RVs?

Hey, it’s not all bad news! You have options.

  • Weigh your RV. You don’t have to crunch numbers. You can take your RV to a scale and have all your axles weighed. Then adjust payload from there.
  • Use a calculator. Check out this Travel Trailer Towing Calculator or this 5th Wheel Towing Calculator. While no calculator is 100% accurate, they can point you in the right direction.
  • Research before you buy. I’ve talked with a lot of RV owners who discovered too late that they couldn’t realistically tow their new $75,000 RV. They either had to buy a new $50,000 truck or sit on a $75,000 white elephant. Researching tongue weights, pin weights, and payload capacities should be de rigueur for any RV purchase!
  • Go smaller. I know it’s anti-American, but smaller RVs are the future. You can venture off the pavement, store them in your backyard, and tow them with half-ton trucks. Better to keep your tow vehicle big and your camper small.

I should answer one last question: Is the 80% Towing Margin rule safe?

Eh … it’s inaccurate. For big families and packrats, a 60-70% margin is more practical. But as I warned earlier, if you load up a Chevy Suburban with seven husky people and seven suitcases, you’ll probably max out the GVWR—and you won’t be approved to tow a single pound!

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Tow Pig
29 days ago

I agree that this is a big deal and many people don’t know these details. So, why are so many people towing at their manufacturer’s stated limit which has put them over GVWR? Why are there no standardized laws for matching tow vehicles to campers? Why is there no regulation for RV dealers who seem to sell most people too much trailer with no liability?

Carl
1 month ago

Great article! This information is totally unknown by most folks buying an RV and or tow vehicle. And, many will ignore your advice unfortunately. Another factor is that most RV manufacturers substantially understate the dry weight of the trailer. They will often give the weight without propane bottles, any options, batteries, etc.

Lou
1 month ago

Excellent article. I’ve given up trying to convince stupid people on IRV2 forums that no, you can’t magically increase tow capacity with airbags, and beefier shocks. No, just because you know a guy who tows a giant 5th wheel with a half ton truck and nothing happened doesn’t mean it’s safe, or that something catastrophic won’t happen. Some people just want to hear what they want to hear.

Gordon Oliver
1 month ago

Great advice to consider. It’s not quite like bringing 4 people and extra ice chest, chairs, etc. In tow vehicle and still be able to tow that maximum weight safely. I have had salesperson tell me my vehicle can tow 9000 pound trailer but never mention of other weights to consider.

Matt C
1 month ago

Good article! As a fourth generation professional truck driver with almost 2 million miles. I have seen a lot over the years. Many professional drivers would like to see some type of licensing requirement for RV’s and utility trailers. Many who have a Operator’s License lack the understanding of the basics like Pre-trip inspections, GCWR, GVWR, weight distribution, hitch weight, load securement, backing, proper lighting, fatigue, blind spots, etc. Unfortunately these things are overlooked or just not understood. As this article points out about maximum towing capacity.

Since we’re not likely to see anything done with licensing. It would be nice to see the RV industry or a group like Good Sams have a 2 day schooling, similar to what ABATE does for motorists. Many times on successful completion of the ABATE schooling your insurance company will give you a discount.

We all need to work together to make the roads safer for everyone!

Last edited 1 month ago by Matt C
Deadarmadillo
1 month ago

No, I didn’t enjoy the article. I’m an engineer also although not an RV engineer. If the industry is so concerned about proper match up of towed RV vs. tow vehicle they would simplify capacity information so Joe Sixpack (or maybe even *** *******) could understand it. They would have load leveling hitches included with all travel trailers. Also, all engineering disciplines that I know of have “fudge factors” designed into their products. I’ve been towing rv’s for years and while I’m cautious, I’m not fanatical and have never had a problem. I know, you probably will shoot off the last word and yadda, yadda , yadda. But, I think the evidence is that problems from overloading pale compared to the multitude of other problems that will plague that new RV that someone is buying right now.

Bob p
1 month ago
Reply to  Deadarmadillo

Your name says a lot about you, from the way you talk you may be like Jerry Clower said one time. You may be educated far above your intelligence.

Wallace Wood
1 month ago

Besides the weight rating of the axles and towing capacity of the pulling vehicle people should consider the licensing requirements.
In the state of California maximum weight of a trailer with a ball hitch with a regular license is 10,000 lbs a fifth wheel trailer 14,000 lbs.
Over those weights and you need a class A license.
CHP will enforce these laws. A friend of mine had his trailer impounded by CHP

Peter
1 month ago

This is a great article. Before we bought our 22V Ice Castle, I did a ton of research
on this very topic. I determined our 2017 Ford Expedition Platinum MAX with 9200# towing capacity couldn’t tow it due to the 15% tongue weight of Ice Castle. It put us at the near the maximum GVCR with just me in it. I would like to see an article to see if weigh-safe weight distribution hitches are hype or worth the investment.

Gord
1 month ago

Great article! Now how about an article on trailer weights and numbers?

bill
1 month ago

Finally an expert who is willing to explain gcvwr to gvwr!
Thank you for affirming what a few of us have been trying to make known for awhile.

Bob p
1 month ago

This article should be required reading for anyone shopping for a tow vehicle or RV. The same basic info should be for people pulling toads! Truck manufacturers are not print the disclaimer in large print about the particulars of the tow truck, and RV salesperson is not concerned whether you’re going to be safe towing the rig they’re selling you, only the sale, if you don’t investigate for yourself you’ll find out the hard way in an emergency.

captain gort
1 month ago

My big SUV is rated to tow 7200#. My little 21′ “lite” trailer weighs 4400# empty and about 5500# ready for the trip. However- my SUV is maxed out. Per the numbers (and its only my wife and I) when the SUV is loaded with the stuff we always bring with us; ie, a small generator, some bottled water, etc…the GVWR and rear axle rating are maxed. The SUV handles it just fine. I use a reputable WD hitch. I’ve weighed the rig carefully- yup, its maxed.
I see people towing preposterous things: like a V6 RAV4 towing a 25′ trailer and the owner bragging about it. Oh sure- it has pull power…but grossly insufficient chassis capacity. Or very short wheelbase vehicles…sway!! If he gets into an accident and hurts somebody, a good lawyer will eat him alive for gross criminal negligence…and maybe the dealers, too. All the numbers will become irrefutable evidence and guess who’s going to lose!

Bob p
1 month ago
Reply to  captain gort

If you’re overweight you might want to take some of your own advice, the same ambulance chaser you’re talking about will be all over you.

Som
1 month ago
Reply to  Bob p

Ambulance drivers will be watching everyone and siren sounds to pi** everyone.

captain gort
28 days ago
Reply to  Bob p

I said its maxxed…but it does NOT exceed the maximum. Its within limits.
The point is that a big “tow rating” does NOT mean you can tow something that heavy -or long. You will inevitably exceed axle/tire limit ratings before you reach that “tow rating” in most cases. I’m a geeky Mechanical Engineer. TV ratings are pretty much useless. You have to dig a lot deeper to find the weak spot

Rebecca
1 month ago

Wow…just wow

Tony Barthel
1 month ago

This is incredibly share-worthy content that every vehicle salesperson should be required to know before getting their license. Great, great information.

I hope everybody who reads this shares it with their friends, quite honestly.

Steve Comstock
1 month ago

Great article! Sort of “addressing the elephant in the room.” This is the type of information that is most important to the RV Travel readership. Thank you for your contribution.

Steve H
1 month ago

RV companies have engineers? That’s the biggest takeaway in this article for me, a retired engineer!

But there is another factor to consider besides weight–frontal area of the RV, ie, drag. Most 1/2-ton truck owner’s manuals will have some fine print at the back that the trailer frontal surface area should not exceed 60 sq. ft. That means an 8′ wide, 8′ high (above the frame) travel trailer already exceeds that rating. Think that four square feet is “nothing”, think again! And, if that frontal area is corrugated aluminum siding, REALLY think again.

Ron
1 month ago

80% of people that tow are overweight and under powered. There is a huge liability factor not mentioned if in an accident and overweight.

Bill
1 month ago
Reply to  Ron

You don’t have to get personal!

Admin
RV Staff(@rvstaff)
1 month ago
Reply to  Bill

😆 Have a great day, Bill! 😀 –Diane

Leonard Rempel
1 month ago

Great article! Bottom line is go over on your tow vehicle! Some people told me a 3/4 ton would be “good enough” for my 35′ 5th wheel that was 14,000 lbs dry and max 18,000 lbs loaded. Nope I said and bought a Chevy 3500 Dually diesel. Never breaks a sweat on any type of road condition or incline. That’s what I call peace of mind!

G13
1 month ago

Excellent article providing reader with thoughtful and insights on understanding payload.

Ray
1 month ago
Reply to  G13

Ditto

Bill Fisher
1 month ago

Good article!

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