Single or tandem axle
The van's loaded weight decides it.
Past what one axle can carry, a van needs a second.
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.
Compare the van's ATM (Aggregate Trailer Mass) and ball weight with your car's limits. Axle count does not change those limits, so check both figures on each van.
- Tandem tyres - four instead of two (so each tyre, bearing and brake carries about half as much on level ground 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.
More axles mean more carrying capacity, more hardware to service, and a van that turns differently.
Weight decides most of this for you
Axles, tyres, bearings and brakes all carry ratings. The running gear has to be rated for the load on it with the van at its ATM. ATM is the most it may weigh fully loaded.
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. You only need to choose when two vans on your shortlist are close in size and build but have a different number of axles.
What your car has to tow
Every towing limit is a weight limit. The braked towing capacity, the towball limit and GCM (gross combination mass, the most the car and van may weigh together) are all measured against the van's ATM and its ball weight. Axle count does not change the car's limits. Compare each van's ATM and ball weight.
Put both vans through the tow calculator to compare them on those two figures.
Turning, reversing, and pushing it by hand
A single axle turns around a point close to itself. It turns in a tight arc and responds quickly to a small correction.
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.
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.
The manoeuvring gap counts for more on unformed tracks and bush sites, where 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 and bearings as a single axle, and often 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 a tandem has more of each.
Each one is also doing less work. At the same loaded weight on level ground, four tyres carry about half what two would, and the same halving applies to the bearings and brakes underneath them. Without load-sharing suspension, one axle can take more over bumps, so each is rated with a margin.
Over 2,000kg GTM (Gross Trailer Mass), every wheel must have brakes. Up to 2,000kg GTM, brakes may be on one axle only.
If a tyre fails
If a tyre fails on a tandem, the other wheel on that side still carries the load. A single axle has only one wheel on each side.
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 to keep on the road depends mostly on the kilometres you do and the roads you drive. The running side of ownership is set out in caravan running costs.
Which one suits the way you travel
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. Look at their ATM, tare and payload, and how each fits the car you have or plan to buy.
Our comparison tool puts two vans side by side, axle count included. Each van's own page on our site carries the same figures.
Axle questions, answered
Is a tandem axle caravan safer than a single axle?
The clearest difference is that a tandem still has a wheel carrying that side of the van if a tyre fails. Beyond that, keep either van inside its ATM and GTM (Gross Trailer Mass), and its loaded ball weight inside the car's towball limit. Hitch it so it sits level.
Can I tow a tandem axle caravan with the same car?
Axle count does not change your car's limits, so a tandem works with the same car if its ATM and ball weight fit them. Two vans at the same ATM can carry different ball weights, so compare each van's ATM and ball weight.
Is a single axle caravan easier to reverse and manoeuvre?
In tight spaces, yes: a single axle turns in a tighter arc, while a tandem's tyres drag sideways in a sharp turn. A tandem holds a straight line more willingly when reversing.
Do tandem axle caravans cost more to run?
A tandem has twice the tyres and bearings, and often twice the brake assemblies, to service and replace. Each does about half the work on level ground at the same loaded weight, so price the consumables against the van you are looking at.
Why do some caravans have three axles?
They need the extra capacity. Once a van's loaded weight passes what two axles can be rated to carry, a third axle carries it. Tri-axle vans sit at the heavy end of what gets towed behind a road vehicle.
Compare the two vans side by side
Put the single and the tandem next to each other, and check the ATM and ball weight each asks of your car.