Which Is Better – A Single or Double Axle Travel Trailer? (An Engineer’s Perspective)

If you’re the sort of person who enjoys dog fighting, political debates, and Brazillian soccer matches (football, my apologies), then just ask a group of RV owners, “Which is better? A single- or double-axle trailer?” Then sit back and watch the hornets fly.

Personally, I don’t get what the fury is all about. Double-axle trailers are obviously way, way better.

I jest! Like most design questions, it depends. Both have their pros and cons, and I’m going to show you which is which. Because sometimes, one really is obviously better.

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Table of Contents

Pros of a Single-Axle Trailer

Lighter Weight

Single-axle trailers tend to be smaller and more lightweight. And while that may not be exciting for you, just remember, your SUV probably can’t tow what you think it can!

If you’re really counting the calories, then the weight of the axle assembly itself is a big deal. An axle assembly with tires and brakes can weigh 150-200 lbs!

Costs Less

I won’t spend much time on this reason because it’s fairly obvious: fewer parts = less cost to purchase.

Unfortunately, this sometimes means that manufacturers will skimp on a double axle in favor of a “strong enough” single axle. However, the single axle may lack sufficient GAWR. This is why you must pay careful attention to the Cargo Carrying Capacity!

Cheaper to Maintain

Theoretically, a single-axle trailer is cheaper to maintain because you only have to service one set of brakes and replace one set of tires.

HOWEVER – and it’s a big however – that assumes that both trailers have the same GVW/GAWR ratio. If you’re consistently overloading or maxing out your GVWR, which can be tempting on a single-axle RV, you will wear out components much faster. I’ve seen tires go kaput less than a 1,000 miles! For some reason, tires on single-axle trailers seem to be more susceptible to camber and alignment problems. So have your RV inspected annually!

Easier to Maneuver

I use the word “easier” here reluctantly because short, single-axle trailers can be a bear to back up! But if you’re driving twisty roads or pulling into a cramped campsite, a single-axle trailer is much more nimble and responsive.

Easier to Hookup

A single-axle trailer can often be slightly rotated using a trailer valet or by hand if the A-frame jack has a castor wheel. This makes it much easier to hook up if you don’t have a rearview camera on your tow vehicle.

This is one of the reasons that Bowlus, which manufacturers a luxury travel trailer similar to an Airstream, chooses to use a single axle.

Easier to Park

Single-axle trailers tend to be smaller (22-ft in length and below). Smaller RVs are easier to park, tow, and store. Many tow vehicle and single-axle trailer combinations will fit in just two regular parking spaces (36-40 ft).

Better Off-Road

There’s a reason you don’t see very many double-axle off-road trailers. They just don’t handle sharp turns and steep approach/departure angles. They may struggle on high-clearance 4WD roads where a single-axle trailer really shines.

In fact, in offroad applications, a single tire may be responsible for supporting the bulk of the entire RV! So unless you want extremely heavy, ridiculously oversized axles and frame, it just doesn’t make sense.

Can Tow Off-Level

This isn’t an excuse you tow a single-axle trailer – or any trailer! – off-level. But if you do, then the results aren’t usually as catastrophic.

Tow with the nose up, and you’ll decrease tongue weight. Tow with the nose down, and you’ll increase tongue weight. But the change should be less than +/- 5%. Unless you have zero reserve capacity on your tires, your travel trailer should be fine.

But if you tow a tandem-axle trailer off-level, then you’ll overload one set of tires! Huge, huuuuuge problem. For that reason, you must be zealous about leveling. You can use a bubble level to check level, or measure the height from ground-to-frame at each end. They should be within ½” of each other.

Pros of the Double-Axle Trailer

Better Stability

This is THE #1 reason people choose a tandem- or triple-axle RV. The trailer will naturally track better, like a baby duckling. And the trailer is naturally more resistant to side sway.

As someone who has owned both types … At highway speeds, I do like the ride of a double-axle trailer over a single-axle.

However, I’ve towed single-axle travel trailers thousands of miles across the country with literally zero problems: no sway, no porpoising, nothing.

So yes, the scales tip in favor of double-axle trailers … but I wouldn’t arbitrarily say no to a single-axle trailer even if drove 10,000 miles a year.

Bigger Payload Capacity

Usually, a double-axle trailer has a larger payload capacity (aka cargo capacity) than a single-axle trailer of the same size.*

You can never have too much payload capacity! Even if you don’t use it, you’ll extend the lifespan of your suspension by giving it some breathing room.

Double- or triple-axle suspensions are standard on 5th wheels, toy haulers, and other heavy-duty RV types. These RVs, especially toy haulers, may need 4,000+ lbs of cargo capacity. You won’t get that with a normal single-axle suspension!

Braking Performance

I hesitate to even include this one because it completely depends on the trailer! So it’s not always true.

Here’s the thing: Tow vehicles assume the camper trailer will stop itself, more or less. So a tandem-axle trailer has better braking performance only if both axles have brakes – and many don’t!

And obviously, the quality of the OEM brakes and the type of brake controller you use will make a major difference.

Easier to Reverse

Tandem-axle trailers don’t turn on a dime like single-axle trailers do. If you’re backing up a 100-yard driveway, you know how important this is!

With that said, don’t let the fear of driving an RV for the first time dissuade you from the trailer of your choice. As you gain the skill, you can pilot either one.

Easier to Change a Tire

Sometimes, you don’t even need a bottle jack to change a tire on a tandem axle! (so long as you don’t overload the remaining tires.) Just raise or lower the trailer frame with the tongue jack.

FAQs About Single Vs Double Axle Trailers

FAQ: Can Double-Axle Trailers Carry More Weight than Single-Axle Trailers?

You have heard it said that trailers use double axles to carry more weight than a single axle. That is … mostly true.

If I was dead set on designing a single-axle trailer with a GVWR of 10,000 lbs, I could do it. No problem. Lippert makes torsion axles rated for 12,000 lbs. Dexter makes sprung axles rate for 16,000 lbs.

But … you might not like it. Because unlike all your friends with normal RVs, you would require “specialty” parts: bigger tires, bigger hubs, bigger brakes, etc. These parts can be hard to find outside of a semi-truck service center. And these suspension parts get exponentially more expensive as they get bigger!

So it’s not that we can’t design single-axle trailers for big loads. But it’s much more convenient for the customer if we split the load across two or three smaller, cheaper axles with more readily available parts. You’re welcome.

FAQ: Is a Single-Axle Trailer Safe?

RV Blown Tire Flat
“Flat Tire” by TireZoo is licensed with CC BY 2.0. To view a copy of this license, visit https://creativecommons.org/licenses/by/2.0/

Yes, single-axle trailers are safe.

The reason why some people preach that a double-axle trailer is safer is because in the case of a tire blowout, you can pull over to the side of the road on the remaining tire.*

And that’s a great point. However, if you’re afraid that a tire blowout will lead to a complete loss of control, that’s pretty rare from my understanding. Remember that in the event of a blowout or run-flat, the trailer should just ride on the rim.

I haven’t personally read anything from NHTSA that says tire failures on single-axle trailers are inherently more dangerous (or likely to cause a rollover) than failures on multi-axle vehicles.

But! … a trailer with a blowout will pull harder toward one side than the other. If you’re towing a very large RV with a small tow vehicle, that could overwhelm the tow vehicle – and that could be catastrophic! Which is a great reason to always have a weight-distribution hitch.

Of course, the best thing to do is make sure your tires have plenty of reserve capacity and that you’ve weighed your RV!

*Do NOT assume that the rest of your tires are safe! In fact, you’ve almost certainly overloaded the remaining tire on the side with the blowout, and you’ll either need to have it dis-mounted and professionally inspected – or better yet, a new tire.

FAQ: Does a Single-Axle Trailer Get Better Fuel Economy?

I’ve heard this claim several times, but I’ve never seen any numbers or studies supporting this assumption. I’ve normally seen it said that less weight = better fuel economy, but as I’ve explained before, a few hundred pounds in a typical RV will barely affect your fuel efficiency.

So unless there’s some serious aerodynamic benefit to a single-axle trailer that I don’t know about, I remain firmly skeptical about this claim.

FAQ: Do Double-Axle Trailers Hold Their Resale Value Better than Single-Axle Trailers?

This claim is oft-repeated, but it’s misleading. If you were shopping for a utility or cargo trailer, then yes, people pay more attention to the number of axles.

But when you’re selling an RV, the condition matters much more than the number of axles. Besides, depreciation is going to kill your resale value anyway!

Do double-axle RVs sell for more money than single-axle RVs? Sure – but that’s because double-axle travel trailers tend to be all-around bigger and nicer. Don’t blame the axle!

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Ross
Ross
RV engineer by day, intrepid blogger by night (and occasionally weekends). This website is all about how RVs work, and sometimes why they don't.

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