If you are in the market for a new caravan, and can’t decide whether its best to get one with two wheels, or four, this post will give you the ultimate run down. Single axle vs dual axle has been a raging debate for a long time, and each option has its own pro’s and con’s.
With everything, it will depend on how you use your trailer as to what you choose to go with, but you’ll generally find most people sway one way or the other with no interest in the other style. That said, there are some specific differences which we go into below:
What’s the benefit of a single axle van?
They are lighter
By the very nature, a single axle caravan will weigh less. Suspension isn’t light, even if you have the independent suspension that many people are getting today.
By the time you add up the weight of the suspension components, two extra tyres, wheels, brakes and hubs, you can be up to several hundred kilograms heavier. Of course, with two more tyres you can generally carry a lot more, so its a trade off that you have to consider.
They require less maintenance
The more moving parts you have, the more maintenance there is. Single axle vans only have two tyres, two brakes, two hubs and two sets of suspension to contend with. The moment you go to a dual axle van, you have double that. That means twice as long to replace, or repack the wheel bearings, twice the suspension to replace when it wears out and so on and so forth.
This means that the maintenance is not only more time consuming, but it costs more. It might be $550 for two new tyres, but its $1100 for 4. Again, not a deal breaker, but it is something to be mindful of.
Single axle vans are easier to manoeuvre
If you want to be able to get a van into tight places, a single axle van will win every day of the week. If you don’t believe me, compare a normal light weight box trailer to a heavy duty tandem axle one. The latter is significantly harder to move around, and their turning circle is substantially worse due to the tyres fighting each other.
If you watch a tandem axle van being turned on a sharp angle, you”ll hear and see the tyres fight each other, and that does your manoeuvrability no help. To be fair, caravans aren’t exactly small in the first place, so the loss of manoeuvrability may or may not bother you.
My Dad specifically wanted a single axle van for this reason, and you have to decide whether it matters to you, or not.
They are cheaper
Single axle vans are cheaper, because there is less involved. You have half the number of tyres, wheels, brakes, hubs, bearings and so forth.
They require less work playing with tyre pressures
If you have 4 wheels, plus the 4 on your car, you are in for a long time to reduce, and reinflate tyre pressures when off road. You should be doing this regularly for anything that isn’t a bitumen road, and that means more time mucking around.
Benefits of a dual axle van
You generally have a greater payload
The more wheels, the more payload, in general. You’ll find that tandem axle vans generally weigh more to begin with, but also have a significantly greater payload (the van’s ATM minus the tare). This is pretty simple physics, as you have more surface area to spread the load over.
Stability is improved
In general, a dual axle van will be more stable to tow than a single axle. This might not always be the case, especially if they are poorly loaded, but dual axle vans are inherently more stable.
It’s safer if a tyre blows
Having a tyre blow when you are ticking along at 100km/h isn’t much fun in a car, trailer or anything else. When you are towing a big van behind you though, and a tyre goes bang, with nothing else to support it except the one on the other side. If you have dual axles though, the other tyre will take the load and you’ll have ample time to pull over safely and deal with it. In fact, there have been people who’ve had a tyre fail on dual axle vans and have driven for many kilometres after without even realising.
You will know if a tyre goes bang on a single axle van, within a matter of seconds. Luckily today, there are some fantastic tyre pressure monitors which will alert you should something go wrong, and they can save you a lot of heartache.
You have better flotation on sand
When you are rolling down a soft beach, the more surface area (generally in length) the better you will float. This is why vehicles with big tyres that aren’t too wide do well on the beach. A dual axle van spreads their weight over 4 tyres, instead of 2, which means you get more flotation.
As an example, a 2.7 tonne van on two wheels will have its weight distributed over two patches, carrying 1350kg each. The same van, with 4 tyres has it distributed over 4 patches, carrying a mere 675kg per wheel. This is how tanks can float over surfaces; its spread over so much that the weigh applied to each patch is less than what you’d apply by walking on your own two feet!
Its worth noting that you have marginally more drag towing a trailer with 4 tyres down a beach, but the flotation would make up for some of that. It’d make an interesting experiment!
You can run normal rated rims and tyres
As you are able to spread the load over 4 wheels, the rims that you have on a dual axle van are generally normal rims with standard weight ratings. If you are towing a heavy van on two wheels only, the rims and tyres need to have a much higher weight rating – sometimes up to 1500kg per wheel!
Dual axles have better entry and departure angles
Single axle vans have worse entry and departure angles, as there’s only one set of wheels giving the van clearance. An identical van with two axles will have better entry and exit angles, as each axle is moved further forward or back.
Other factors to consider
What can your vehicle tow?
At the end of the day, all of this is null and void if you don’t have a suitable vehicle, and a lot of people fall into this category. The towing capacity of most 4WD’s these days is just smoke and mirrors, and a complete marketing farce. To find out what you can actually tow, have a read of this: Towing Capacity; a simple guide to keep you legal.
More brakes means you can apply more braking force. With twice the surface area contacting the ground you should be able to brake better, but it depends on how much heavier the van is that we are talking about.
At the end of the day, there are lots of fantastic vans out there. Some will suit one particular set of travellers, and not another, and that’s just great. You need to get something that suits your requirements, and that you can legally tow. Get that right, and you’ll be able to enjoy your van as a pose to looking for something else to replace it with!