The truth about overweight caravans

More than half the caravans checked by a mobile caravan weighing service have been found to exceed their ATM (Aggregate Trailer Mass), which is the maximum travelling weight stimulated by their manufacturer.

Meanwhile, nearly a quarter of all tow vehicles checked exceeded their GVM (Gross Vehicle Mass), which is the permitted  total weight of the vehicle including passengers, fuel, after-market accessories, cargo and the towball weight of the caravan or camper behind them.

What is frightening, though is that the figures are based on people who are genuinely concerned enough to have their weights checked, and there's a bigger majority out there that put their head in the sand and say ‘she’ll be right’ ! (The figures are also similar to that discovered during a Victoria police blitz held last year, where more than half the caravans pulled over were also found to be over-weight.)

Reality check

I confess that until recently, I was in the latter 'she'll be right' group, albeit based on some experience as a long-time caravanner and reviewer. But when I borrowed a 2018 Isuzu MU-X to tow my Trakmaster off-road caravan to the Gulf of Carpentaria and Lawn Hill National Park, I decided to check my weights for the very first time.

A prime reason is that the MU-X with its gutsy 3.0 litre four-cylinder diesel engine is rated to tow three tonnes, whereas my personal 2008-model Land Rover Discovery TDV6 can haul 3500kg. So, with similar loading in the caravan and tow car, I wanted to be sure I was legal, but from a personal credibility and insurance viewpoint. I guessed correctly I was OK, but the result was much closer than I thought!

I don’t know about you, but getting away on a big trip is a bit chaotic for me. There are cats to find, catch and take to the cattery; neighbours to convince to water precious plants, collect mail and bring in the bins; storage spots to find for all the things you have remembered to take (not to mention the ones you always forget!), fridges to charge, water tanks to fill and last-minute drinks and groceries to pack.

We always intend to make an early start, but we never do and by the time we’re on the road all we want to do is put some distance under our wheels, not spend half an hour or more holding up trucks on a public weighbridge while we weigh our rig and then unhitch to establish separate weights and the ball loading. So, like most travellers, we don’t.

Pre-trip weigh-in

However, the Weightcheck Mobile Caravan Weighing, comes to you. In our case it was early on the morning of our departure, so we missed morning peak hour while founder, Brisbane-based Dave Lewis, went about his thing.

The concept of Weightcheck is about making the process of checking the weights of your caravan and tow vehicle, a whole lot easier. Public weighbridge dockets record three weights, but provide very little other information.

In contrast, Weightcheck’s written report is a document that's easily understood by the caravan owner and gives a detailed explanation of the weights and what they all mean. Moreover, as they're a licensed weighbridge, their document is accepted by Queensland Transport and similar authorities in other states, which is very reassuring if your trip goes pear-shaped!

Scientific process

The starting point is smooth surface, ideally level, although this is not essential, as Dave’s equipment can be re-calibrated to allow for moderate slopes.

First, the laden van with full water tanks is weighed, with a portable scale under each of its wheels to establish axle weights. For this task, the towball height is set to exactly where it was when the van was attached to the tow car to ensure a reliable ball weight. Experience has shown Weightcheck that 50mm difference in coupling height can record a difference of 20kg or more.

My tandem-axle Trakmaster Pilbara off-road caravan has a Tare (empty) weight of 2432kg and a maximum ATM of 3200kg, which means I’m able to carry a total payload of 768kg (although I never come near that).

This was confirmed by Weightcheck’s figures, which showed that fully laden it tipped the scales at 2641.5kg; well under its compliance rated Gross Trailer Mass (GTM – the maximum permissible weight of the van excluding its towball) of 2950kg.

Then came the towball mass, which at 270kg was right in the sweet spot of the preferred range of 8-12 per cent of Tare weight. Added to the GTM, it meant that my van’s ATM of 2921kg was comfortably below its rated 3200kgh. Are you still paying attention?

Then it was the turn on the scales of the MU-X, which has a compliance-plated GVM of 2750kg and a GCM (Gross Combined Mass, or the maximum weight that the tow vehicle and caravan can be together) of 5750kg.

Laden with three quarters of a tank of fuel, my wife and me, a petrol generator, 45-litre fridge, off-road recovery kit, tool box and portable BBQ, it came in at 2418.5kg for the laden vehicle alone, but adding the 270kg towball download brought its GVM up to 2748kg – phew, just made it by two kilograms!

Had it been over, I would have had to start leaving some things behind – not you darling! – but it just squeaked in.

I had planned to put a 16-inch spare wheel and 265-section General Grabber tyres for the Trakmaster on MU-X’s optional roof bars, but in light of the above, thought better of it and left them at home...

Things looked better when you compare adding up the GCM of both tow car and trailer though, with the Isuzu-Trakmaster rig weighing in at 5339.5kg, against its allowed 5750kg GCM.

Learning curve

So, what does all this tell us?

For a start, no matter how experienced you are, it’s not hard to fall foul of the regulations, potentially leaving you open for charges, or even insurance denial, if you have an accident.

Dave Lewis from Weightcheck said the highest over-weight reading for a single axle caravan he had recorded in 12 months of business and more than 180 caravans was 618kg over its ATM, while Weightcheck’s ‘record’ for a tandem axle van was 485kg.

Towball overloading is also a common issue, with many vans carrying up to 100kg more than the tow bar and vehicle manufacturer intended, leading to potential component failure.

Imagine the extra forces that are exerted on the rear of the vehicle when you hit the bottom of a dry ‘dip’ on an outback highway and how these forces add to the load placed on your tow vehicle’s rear tyres!

For an all-up cost of $200, plus GST for an on-site, pre-trip check, I reckon that’s the cheapest travel insurance you can buy!

Related reading:

Overweight utes threaten road safety

Towie enters weight debate

Overweight vans caught in blitz