Caravans

Tandem

One for the tandem is when you go off the edge of the road the van doesn't pull the vehicle around as much.
Two the carring weights change.
Three you got three other tyres holding the thing up if you get a flat.

Single
Turning circle is smaller
maintenance is two times less.
Cant carry as much crap.

That's a females view and we have had both.

Cheers
Sharon

Hello feathery, our first van was a 16' single axle pop top with a tare weight of about 1100 Kg & we have now progressed to a 19' tandem axle, also a pop top & it tares at about 1700 Kg
Our only reason for changing was we wanted a bigger van with a few more creature comforts.
We tow with a Mazda BT 50 & have not noticed any difference in towing characteristics.
Some people will tell you that a single axle van is unstable & will wobble all over the place on the road & consequently stored items get tossed all over the place. We did not have that problem & we have followed many single axle vans on the road & they all appeared to track in a stable manner. This is supported by many single axle van owners.
I don't know whether it is an advantage or not, but because the weight of a dual axle van is distributed over four wheels, you are able to run your tyre pressures a little lower & maybe you are in a better safety situation if you have a flat.
If you need to manually push the draw bar on a single axle van to straighten it up a bit, it is easy to do so on a single axle van & just about impossible if you have a dual axle.
I think the number of axles is dictated by the weight of the van, so work out what size van suits your needs and go for it. Good luck & cheers

Mate currently I have an 18' Tandem axle pop top van. Have towed it behind a Ford Falcon & 2 GU patrols. The one thing I find is it rolls behind your vehicle much easier, feels much more stable & if you have to move suddenly on the road it feels much safer. Previous to this had a single axle and always felt unsure that in an emergency or high wind it was not quite safe.
I have been towing vans for 45 years with a lot of mileage behind me & for the extra it costs I feel much safer with the tandem behind me.
Good luck

My husband insisted on this one.

Our previous van was a small single axled wind-up. Advantage - could spin it round by hand if stuck. Disadvantages; stuff was tossed from one side of the cupboards to the other (we travel off the bitumen frequently), damage to fittings, milk bottles and cartons leaking from the bottom from the bouncing. I wouldn't even try and take eggs! Husband's reasoning had more to do with safety in case of a blowout or losing a wheel, and general stability of the unit. There is also less thrust up and down on your tow hitch with the van stable on dual axles.

We now have a tandem axled 18' caravan, and everything rides smoothly. I am well and truly convinced.

Motherhen

By the very nature of your question, it seems that you don't have any understanding at all regarding the use of single or dual axles. That's OK so long as it's clear that you don't actually specify which axle combination to use whn building/ordering a van. Such choice is dependent of factors such as weight, length etc. Manufacturers have established formulae based on 'sound' engineering principles. Most of the advantages have already been mentioned.

You need to consider how you will use the van. 18' for a single axle will be pushing it for most manufacturers. You can just do it with a heavier axle, bigger and better wheels and tyres, but as Mother said - not the best option for most uses.

The big advantage of a single axle is less weight, better manoeuvrability, and cheaper, but the trade offs are very real.

If money is not an issue go for independent suspension in whatever you choose!