Single axle or tandem?

NoelB · Veteran Member

Single axle or tandem?

Peter_n_Margaret · Guru

I would only ever choose a single axle. Adding a second axle adds a lot of weight that is better not there or used for something else.
Cheers,
Peter

SoloMC · Senior Member

Tandem gives a better ride and better safety if one gets a blowout (never happened to me over 20 years)
ive found that tandems tend to put more pressure on front wheels of van
single allows a better turning circle without ripping things up

erad · Guru

Have a look back in this section - currently about 10 entries down on Page 6. This topic was discussed at length. MY opinion - for your needs, a single axle van will do the job quite well. People reckon the dual axles are more stable, especially in the event of a a blowout. I have towed single axle caravans well over 150000 km, and had 4 blowouts. Each time, the only thing I knew was either excessive drag (apparent loss of power), or excessive noise. No swaying, no skidding, just a lot of noise, including some from me. An extra axle adds about 100 kg to the weight of the van, and unless this is required to carry the load, it adds extra friction drag (more fuel consumed to travel the same distance) and more things to go wrong (bearings, tyres and brakes).

If you are leaning towards a single axle van, I would seriously check the load carrying capacity of the tyres and wheel bearings. A 17.5 foot van is near the upper limit of single axle vans.

NoelB · Veteran Member

Thanks - great tips

Mike Harding · Guru

I'm no expert in this area but I think it all comes down to the weight you intend to carry.

I live in my van and don't think I could carry all my junk in a single axel van - maybe I need to get rid of some junk? But I don't want to :)

Rob Driver · Guru

NoelB

If you final decision is to go with a single axle van then apart from you ensuring you comply legally with weights and dimensions it is a good idea to fit tyres rated LT or similar.
That rating is Light Truck and those tyres have a much higher rating with carrying capacity compared to the passenger tyre size equivalent.
Apart from handling the weight more effortlessly, they will cope much better with hot weather and road temperatures as well as being stronger in the walls of the tyre which may help if you are travelling off the bitumen roads. A passenger tyre may more easily suffer damage in the sidewall with rocks.

If you choose a van with semi elliptic springs then shock absorbers would also be a good choice.
If your van has coil or independent suspension then it should come fitted with shock absorbers.

Good luck with it all

-- Edited by Rob Driver on Tuesday 11th of January 2022 03:48:48 PM

NoelB · Veteran Member

Cheers Rob

Hylife · Guru

See my avatar.

Same engine in the Hilux wagon as in the Prado.

20' single (independent suspension) semi off road 2.8T

plenty of power and tows like a dream.

oldbloke · Guru

Once you get to about 18" they are all duel axles.
Its either regulated or simple engineering issue. For example, available axles cant carry the weight.

Hitting the road · Senior Member

I'm new here...we just purchased a Jayco Journey outback tandem axle.
I ruminated over single or tandem axle for ages while when still using our Camper trailer.

My decision to go tandem for me at least was largely based on the load per tyre and the fact we will be doing some longer trips and at times on rougher unsealed roads The single axle vans I read up on all had ATM's of around 2000kg which equated to a load of 1000kg's per tyre.

The Jayco ATM is 2655kg which came back to around 633kg per tyre, similar to what the average loaded 4WD imposes. some single axle vans I saw had similar ATM's as the tandem which imo puts a huge load on each set of bearings and each tyre.

Taking in to consideration that we do some beach camping for me spreading the load over 4 load points was a better option than just 2...especially if dragging through sand on occasion...more drag when turning but I also considered that...

Aus-Kiwi · Guru

I can see where single would be an advantage in real
Outback rough areas . As said over 20ft tandem comes good . I would say weight wise ? Its strength verses carrying capacity ! The unsprung weight Vs carrying capacity would roughly be the same . Being a single would require the stronger unit per axle . But then you would want a van that heavy ! Its horses for courses . The single axle on my sons trailer camper is near twice the weight - strength as my tandem car trailer . Given the car trailer hauls way more weight !! (Edit ., Ahh spell, auto correct !!)

-- Edited by Aus-Kiwi on Friday 14th of January 2022 10:43:15 AM

Peter_n_Margaret · Guru

Hitting the road wrote:

Taking in to consideration that we do some beach camping for me spreading the load over 4 load points was a better option than just 2...especially if dragging through sand on occasion...more drag when turning but I also considered that...

Anyone with significant sand eperience will disute that. Most of the drag is at the front of the tyre. Single axle will always perform much better in soft conditions.

Reducing tyre pressures in sand is critical.

Cheers,

Peter

-- Edited by Peter_n_Margaret on Friday 14th of January 2022 10:45:30 AM

Rob Driver · Guru

If we are all considering the very standard and commonly used caravan axle and spring set then yes, its carrying and approved or rated weight may not be suitable for a large single axle van.
There are other choices.

There are axles built with larger stubs and bearings usually from the larger 4wd vehicles and combine these with heavier axle tubing or solid steel axle bar and suitably heavy springs and you may very well have a single axle van with a much better carrying capacity.
This big axle wont negate the need for a suitable vehicle to tow it.
From my experience most larger manufacturers arent interested in changing what has become, their way of doing single axle vans.

JayDee · Guru

We had a single axle van and after our long trip to Tassie back some 10 years ago, we gave it the flick. A lot of sways and also poor performance re med. to strong crosswinds.

It would be Interesting to do homework on single v dual axle van accidents.

Dual axles are the best option, in my opinion.

Jay&Dee

Rob Driver · Guru

If anyone is considering building or modifying a single axle trailer then this is a good spec to follow.

Generally speaking, look for trailer axles with more capacity than you need. Also, be sure to match springs and tyres, because the real capacity is the lesser of Axle Capacity, Spring Capacity, or Tyre Capacity. Dont get caught short.

The weight rating of the road wheel and wheel bearing pack is to be considered when rating the tyres as well.

Actually speaking the same observation is for a trailer with multiple axles as well, it just involves a little more calculation and design.

The options with a trailer axle today have many different designs. It is not just a simple selection of a leaf sprung axle anymore.

86GTS · Guru

Traveled around 120,000 kms over the past 12 years with an under slung single axle on-road caravan.
All types of surfaces & towed it into some quite remote places with care. Never had a problem with it. smile

Onedodger · Guru

I have had both single axle vans and Tandem axle vans.

In my 30 years of vanning they both have there merits .

Single Axle superb under 2 ton atm.

Advantages are, Easy to park and to move around, Great for traversing down tracks being able to do tight turns.

Disadvantages are, weight restrictions due to tyre and axle capacities, Usually under 19ft long so less room.

Tandem great over 2ton atm.

Advantages are, Can carry more weight and can easily fit in a full ensuite with more room to swing a cat.

My current van is an outback 19'6 inch tandem fully self contained and tows like a dream with ATM of 2972kg at any speed .

The way any van is loaded and set up is critical to its towability.

There are many vans that are not set up by the manufacturer for great towability.

Just My thoughts.

Hitting the road · Senior Member

Thanks for the comment Peter...I have done a heap of sand driving pulling a single axle camper trailer...to the top of Fraser Island several times, to Flinders Beach at Straddy and along quite a number of other sandy access tracks here and there... weight of that camper though was only around 1400kg's, a good tonne lighter than this van. In fact I'd fitted wider rims and fatter tyres to the camper to gain additional flotation which for me worked well.

I'd often drop tyre pressures on the camper trailer to around 12 PSI and would even drop the tow vehicle to as low as 12PSI at times due to light tare and stiff sidewalls on the muddies...

As you wrote, tyre pressures play a huge part in how off road adventures end up...but that said, I have seen plenty of tandem caravans and heavy boats on tandem trailers in soft sand plowing their way through. All it really takes is consideration of the track ahead, a decent tow vehicle with some weight, torque and some momentum...oh, and some smarts...lol

I admit i have zero towing experience of a tandem axle caravan in sand, so this van will prove an interesting learning curve when taking on the softer stuff for a couple of reasons....firstly the van track is wider than the tow vehicle unlike a camper trailer, so will have to make it's own tracks, with the front axle punching it's way for the rear to follow...any turns will produce additional drag pulling tyres sideways. That could easily lead to bogging down...

Therefore many of what were easy sand tracks will be a whole new ball game due to above. But I don't plan to let that deter me, there are way too many fantastic places to camp that are off the beaten track...

It is entirely likely that a single axle trailer could be a tad better dragged through sand, even with a 1000kg's per tyre loading each side, but the tandem axle set up I am hoping will be just fine too carrying less weight per tyre and low tyre pressures.

I don't plan to take this van to the top of Fraser where I'd take the camper either, as the tracks up around Orchid Beach can be narrow with plenty of low hanging tree branches which would not be kind to awnings etc...

Cheers

Peter_n_Margaret · Guru

Hitting the road wrote:
the tracks up around Orchid Beach can be narrow with plenty of low hanging tree branches which would not be kind to awnings etc...

I reckon this is that track? Nice drive.

09-10-14am 022E.jpg

Muddies would be the worst choice for sand. The less tread, the better.

Cheers,

Peter

Hitting the road · Senior Member

Yep, that's what it is like...
Muddies are just fine in sand and on the beach. You just have to be more careful when getting wheel spin as you'll dig yourself in real quick due to the tread type.
But properly deflated mud tyres are quite good in sand as they will give that bit of extra grip when you need it...such as when encountering tree roots which there are plenty of in sand tracks, where a tyre with little tread will often have a harder time as they will often just spin against the obstacle rather than grip and climb over it...or even on the many planks encountered on steeper climbs in places.
I've never really had any problem...