Single or tandem axle
The van's loaded weight decides it.
Past what one axle can carry, a van needs a second, so the weight usually decides it.
Your car tows the van's ATM (Aggregate Trailer Mass) and its ball weight, and those two figures are the same under either layout.
Updated . 8 min read • Technical Guide
The van's loaded weight usually decides it: past what one axle can carry, a van needs a second.
Your car tows the van's ATM and its ball weight, and those two figures are the same whatever is underneath.
- Tandem tyres - four instead of two (so each tyre, bearing and brake carries about half as much at the same loaded weight)
- Tight turns - a single axle comes around easier (two axles set apart cannot both follow one sharp arc, so a tandem scrubs sideways)
- What your car tows - ATM and ball weight (the same two figures whatever is underneath the van)
One axle or two, and what follows from it
A single-axle caravan runs one axle with a wheel at each end of it. A tandem runs two axles, one behind the other, with four wheels. A tri-axle runs three.
That is the whole physical difference. More axle underneath means more carrying capacity, more hardware to service, and a van that turns differently.
Weight settles most of it. Handling and the cost of keeping the running gear on the road are what is left.
Weight decides most of this for you
Axles, tyres, bearings and brakes all carry ratings. The running gear under a van has to be rated for that van at its ATM, which is what it weighs fully loaded with water, gas and everything you packed.
That puts a ceiling on what one axle can carry. Past that ceiling, a van needs a second axle to carry it.
So most buyers choose a van and get the axle count that comes with its weight. The choice only becomes real when two vans on the same shortlist are close in size and build and come out differently underneath.
What your car has to tow
Every towing limit is a weight limit. The braked towing capacity, the towball limit and GCM are all measured against the van's ATM and its ball weight. Neither figure changes with the axle count, so two vans at the same ATM ask the same thing of the same car.
Put both vans through the tow calculator and the comparison is on the numbers that actually decide it.
Turning, reversing, and pushing it by hand
A single axle turns around a point close to itself. It comes around in a tight arc and answers a small correction quickly.
A tandem resists the same turn. Two axles set apart cannot both follow one sharp arc, so turning it hard drags the tyres sideways across the ground instead of rolling them around.
You feel it reversing into a tight site, swinging through a narrow gateway, and pushing the van around a driveway by hand. On a long straight run of highway you do not notice it.
The same geometry helps a tandem hold a straight line while you are reversing.
On unformed tracks and bush sites the manoeuvring gap counts for more than it does on bitumen, simply because the turns are tighter and there is less room to shuffle. If that is the travelling you have in mind, read it alongside off-road vs semi off-road caravans.
Twice the tyres, each doing half the work
A tandem carries twice as many tyres as a single axle, twice as many bearings and twice as many brake assemblies.
That is more hardware to buy and more to service. Tyres wear out, bearings get repacked and brakes get adjusted, and there is twice as much of each.
Each one is also doing less work. At the same loaded weight, four tyres carry about half what two would, and the same halving applies to the bearings and brakes underneath them.
The tyre that lets go
Lose a tyre on a tandem and there is still a wheel on that side of the van carrying the load. Lose one on a single axle and there is not.
Carry a serviceable spare on either layout, and work out before you leave how you would change a wheel on the van you have.
What either one costs you to keep on the road depends on the kilometres and the surfaces more than the layout. The running side of ownership is set out in caravan running costs.
Which one suits the way you travel
We are not naming a winner, because the right answer changes with the van and the way you travel. These are the conditions that point each way.
A single axle suits you if
- The vans you like sit at the lighter end
- You will move the van by hand, often
- Tight sites and narrow gateways are normal for you
- You would rather have fewer tyres to replace
A tandem suits you if
- The layout you want needs an ATM one axle cannot carry
- You want a wheel still under that side if a tyre fails
- Long touring legs matter more than tight-site shuffling
- You are happy servicing more running gear for it
If both columns half describe you, compare the two actual vans instead: their ATM, their tare, the payload left between them, and how each one fits the car you have or the car you are going to buy.
Our comparison tool puts two vans side by side with their axle count among the rows, and every range page carries the same figures for one van on its own.
Axle questions, answered
Is a tandem axle caravan safer than a single axle?
The clearest difference is what happens when a tyre fails: a tandem still has a wheel carrying that side of the van. Beyond that, how a van behaves on the road comes down to how it is loaded, where that weight sits relative to the axle, and whether the whole rig is inside every one of its limits. Those apply equally to both layouts. Load either one properly, keep it inside its ATM, and get the ball weight right.
Can I tow a tandem axle caravan with the same car?
Your car tows the van's ATM and its ball weight, and those are the two figures every towing limit is measured against. A tandem and a single at the same ATM ask the same thing of the car. The axle count matters indirectly, because second axles appear once vans get heavy, so the tandem on your shortlist may well be the heavier van. Compare the published ATM and ball weight of the two vans and run the sums on those.
Is a single axle caravan easier to reverse and manoeuvre?
In tight spaces, generally yes, and it comes down to geometry. A single axle turns around a point close to itself, so it comes around in a tighter arc and answers a small steering correction quickly. A tandem resists that, because two axles set apart cannot both follow the same sharp arc, so turning it hard drags the tyres sideways across the ground. The same geometry means a tandem holds a straight line more willingly while it is reversing, and takes more room and more shuffling to get into a tight site.
Do tandem axle caravans cost more to run?
There is more of the wearing hardware. A tandem carries twice the tyres, twice the bearings and twice the brake assemblies of a single axle, so over the life of the van there is more of each to service and replace. Each one is also doing less work: at the same loaded weight, four tyres carry about half what two would. What any particular van costs you comes down to how far you travel, the surfaces you travel on and how well the running gear is maintained, so price the consumables against the actual van you are looking at.
Why do some caravans have three axles?
The same reason the second one appears: capacity. Axles, tyres, bearings and brakes each carry a rating, and once a van's fully loaded weight passes what two axles can be rated to carry, a third is what carries it. Tri-axle vans sit at the heavy end of what gets towed behind a road vehicle, and everything on this page about tight turns and about the amount of running gear underneath applies to them more strongly again.
Compare the two vans side by side
Put the single and the tandem you are weighing up next to each other, and check the ATM and ball weight each one asks of your car.