This guide from The Adventuring Pals breaks down Tare, ATM, and GTM, helping you legally pack your caravan, avoid fines and explore options for increasing your load capacity.

Overview – Why This Matters

This guide solves the critical problem of understanding caravan payload – what you are allowed to load into the caravan. It is for all caravanners, from first-time buyers to seasoned tourers, who need to ensure they are towing legally. You will learn the difference between Tare weight and Aggregate Trailer Mass (ATM), why dealer-fit options matter and how to verify your actual payload.

The usable payload of a caravan is what you are allowed to load into the caravan. This is assuming you have a vehicle that will legally tow it. That includes everything from the water in the tanks, the gas in the bottles and literally everything else you want to carry in and on your caravan. It can be that simple.

But of course, as with most things, there’s a bit more to it.

Understanding Tare, ATM, and GTM

A caravan’s payload is set by the manufacturer. It is the difference between the caravan’s Tare weight – which is what the caravan weighs as it was built and rolled out of the factory – and its Aggregate Trailer Mass (ATM).

The ATM is the maximum weight that the trailer is allowed to weigh. It is the combination of the weight on the axle/s (GTM) and the tow ball mass. This information is conveniently found on the Compliance Plate. However, there could be a bit more to it.

For example, if you have anything that was added by the dealer then that comes off your payload. In fact, any accessories that you fit, such as extra solar panels, batteries, or a bike rack, also come off the payload.

Why You Must Weigh Your Caravan

For this reason, I always find it a good idea to weigh any new caravan, whether it be brand new or second-hand. I also weigh it with full water tanks and gas tanks. That way I know exactly how much “stuff” I can load into it. It’s also a great idea to have the caravan and tow rig weights checked once you’re loaded up as you would be when travelling. This can be done many ways, from DIY scales to professional caravan weighing companies. My favourite, however, are public weigh bridges.

“I weigh it with full water tanks and gas tanks. That way I know exactly how much “stuff” I can load into it”

How to Increase Your Caravan’s Payload (ATM Upgrades)

If after all this you find yourself to be overweight – the caravan, that is – it may not be all bad. There may be options to increase the ATM and/or GTM of your trailer and therefore gain some extra payload in the process.

For this to occur, you will have to consult with an Approved Vehicle Examiner (AVE). They’re called Approved Persons in Queensland and are sometimes, but not always, automotive engineers. To find one, Google can be helpful. Or ask the local caravan sales and service centres – they can sometimes get results. They will assess the components of the caravan. They will let you know if it’s possible to increase the ATM, GTM or both, and also of any works required to get these gains.

What to Expect from an ATM Assessment

I have been lucky in the past and have been given a few hundred kilos’ increase in ATM and GTM with no extra works required. But I have also been unlucky and been given a list of thousands of dollars’ worth of works to gain just an extra 100 kilos in ATM only.

💡 Did you know? Examiners consider things like RV chains, spring packs and axle groups to determine if and how a trailer’s ATM or GTM can change, says State-Approved Person David Metcalf, Nanango Caravan Service and Repairs.

💡 Did you know? Most caravans are classed as Low ATM trailers. They will have their Tare and ATM listed on the Compliance Plate and on the Register of Approved Vehicles as it was recorded ready for service at the importer’s or manufacturer’s facility.

Words and Photos: The Adventuring Pals

Key Takeaways

✅ Must-check before buying: Verify the van’s Tare weight against the compliance plate, as dealer-fit options reduce your available payload.

✅ Legal or maintenance essentials: Weigh your loaded rig at a public weighbridge or find a reputable caravan weighing service to ensure you are not exceeding the ATM or GTM.

✅ Budget planning reminders: If you need more payload, factor in the potential costs of an ATM upgrade, which require assessment by an Approved Vehicle Examiner.