Why you should weigh your caravan

I once heard of someone carrying two pizza ovens on holidays and someone else who routinely used to pack a full eight-setting China dinner set on their annual caravanning holiday.

Either could have been a costly decision if they had pulled into a Department of Transport weighbridge and found out they're too heavy.

Worryingly, most of the professionals in the mobile caravan weighing business find that the majority of caravans are travelling overweight – many by a lot. Seems leaving the kitchen sink at home is not an option for many of us.

Based on official as well as anecdotal evidence, it's not far-fetched to predict that when fully loaded for a family holiday more than half the caravans on the road exceed their ATM (Aggregate Trailer Mass), which is the maximum travelling weight stipulated by the manufacturer.

Many tow vehicles also exceed 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.

I don’t know about you, but getting away on a big trip is often a bit chaotic. There are cats to find, catch and take to the cattery; arranging for neighbours to water precious plants, collect our mail and bring in the bins; finding places 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.

There's the intention to make an early start, but it often doesn't happen and by the time you're on the road all you want to do is put some distance under the wheels, not spend half an hour or more holding up trucks on a public weighbridge while you weigh your rig and then unhitch to establish separate weights and the ball loading.

But there's an easier way; book in early for a 'weight check' like the one we got once from Brisbane-based Weightcheck Mobile Caravan Weighing on the morning of our departure.

For a relatively small cost, Weightcheck’s written report provides a detailed explanation of the weights and what they all mean. Moreover, their ‘Weighbridge Docket’, which is almost identical to the one issued at a Public Weighbridge, is compliant and acceptable to Queensland Transport and, reportedly, by similar authorities in other states, which is very reassuring if your trip goes pear-shaped.

The starting point is a smooth surface, ideally level, although this is not essential, as the weighing 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 caravan at the time had a Tare weight (empty) of 2432kg and a maximum ATM of 3200kg, which meant I was able to carry a total payload of 768kg.

This was confirmed by Weightcheck’s figures, which showed that full laden it tipped the scales at 2651kg, 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 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 3200kg.

Then it was the turn of the tow car, which had a compliance-plated GVM of 2750kg and a GCM of 5750kg.

Laden with three quarters of a tank of fuel, my wife and me, a TJM recovery kit, tool box and a Weber Baby Q, it came in at 2418.5kg for the laden vehicle alone, but adding the 270kg towball download brought its GVM up to 2748kg -- just made it!

Before the weigh-in, I was considering putting a 16-inch spare wheel and 265-section General Grabber tyres on the tow vehicle's roof bars, which would have put us over the limit...

The GCM of both tow car and trailer comfortably came in at 5339.5kg, against its allowed 5750kg GCM.

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.

Towball overloading is a common issue, with many vans carrying up to 100kg more than the tow bar and vehicle manufacturer intended, leading 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 around $300 at the time, that’s pretty cheap travel insurance.