Caravan Weights Explained: ATM, GTM, Tare & More
Say you’ve been dreaming about hitting the open road for a while. It’s just you, your loved ones, and nothing but Australia’s beautifully rugged terrain stretching out ahead.
Then you start researching caravans and the dream gets a little… complicated. Terms like ATM weight, GTM, tare weight, GCM, and payload capacity start getting thrown around, and suddenly it feels less like trip planning and more like a mechanics exam.
Once you get your head around the basics of caravan weight, you’ll have a better understanding of what your setup can handle, what you can pack, and whether your tow vehicle is up to the job.
TL;DR:
- Caravan weight terms are essential to understand before you buy: Tare is the empty weight, ATM is the maximum legal loaded weight, GTM is the load through the caravan’s axles
- GCM governs the total weight of your tow vehicle and caravan combined
- Water, gas, and gear eat into your payload faster than most people expect
- Always check your vehicle’s tow capacity, GCM, and tow ball rating before committing to a van
Why Does Caravan Weight Matter?
Before you hitch up and head off, here’s why caravan weight deserves your attention:
- For safety: A caravan that exceeds your tow vehicle’s capacity strains your brakes, engine, and suspension. It increases stopping distances and makes the van more prone to swaying on the road.
- Legally: Every caravan has a compliance plate with a legally set weight limit. If you exceed it, you’re breaking the law and potentially voiding your insurance.
- Plan better: Knowing your limits helps you pack smarter and choose a caravan that suits your tow vehicle.
Key Caravan Weight Terms
What is tare weight on a caravan?
Tare weight is the weight of the caravan straight from the factory: completely empty. No water, no gas, no gear, nothing. It’s worth noting that the tare weight does not include full water tanks, which can add hundreds of kilograms once filled. It’s the baseline figure used to calculate how much you can actually load up, which we’ll get to shortly.
What is ATM weight on a caravan?
Aggregate Trailer Mass (ATM) is the maximum legal weight of your caravan when fully loaded, covering everything: water, gas, food, gear, and all your bits and bobs. It’s set by the manufacturer, stamped on the compliance plate, and cannot be exceeded on the road. It’s the most your van is ever allowed to weigh.
What is GTM weight on a caravan?
Gross Trailer Mass (GTM) is the weight pressing through the caravan’s own axles when it’s hitched and loaded. It’s always lower than ATM because it excludes the tow ball download (that’s the portion of weight that transfers onto your tow vehicle’s hitch). GTM is what your caravan’s suspension, brakes, and axles are rated against.
Simply put: ATM = GTM + Tow Ball Download.
What is GCM?
Gross Combined Mass (GCM) is the maximum allowable total weight of your tow vehicle and caravan together, both fully loaded. It’s set by your vehicle manufacturer, not us, and it governs the whole rig as one system.
| Example | Weight |
| Tow vehicle GCM | 6,500 kg |
| Loaded tow vehicle (GVM) | 3,200 kg |
| Remaining capacity for caravan ATM | 3,300 kg |
Think of it as the weight limit for your entire setup, car and van together.
What is GVM and how does it relate to towing?
Gross Vehicle Mass (GVM) is your tow vehicle’s maximum allowable weight when fully loaded, including passengers, fuel, cargo, and the tow ball download from the caravan. A typical tow ball download is 8–12% of ATM, and it all counts toward your vehicle’s GVM.
What Affects Caravan Weight?
The gap between tare weight and ATM closes faster than most people expect once you start loading up. Here are the main culprits:
- Water tanks: water weighs 1kg per litre, so a 300L tank adds 300kg alone
- Gas bottles: weight includes the cylinder, not just the gas
- Batteries and solar: especially relevant for off-road or long-trip setups
- Personal belongings: food, clothing, and gear add up quickly on a long trip
Checking Whether a Caravan Suits Your Tow Vehicle
Three figures need to be verified against your vehicle’s specifications. You’ll need to refer to your vehicle’s owner’s manual or contact the manufacturer for these figures:
- Tow capacity: caravan ATM must not exceed the vehicle’s rated braked tow capacity
- GCM: loaded vehicle weight plus caravan ATM must not exceed the vehicle’s GCM
- Tow ball rating: the expected tow ball download must fall within the vehicle’s rated tow ball capacity
Still Wrapping Your Head Around Caravan Weight Terminology?
Whether you’re planning your next road trip or designing your dream caravan to live in, our friendly team at Lotus Caravans is here to guide you through the process so you can get on the road faster.
Visit one of our Lotus Caravans dealers or get in touch with us today!
FAQ
No, tare weight is measured with empty tanks. A full water load can add significant weight and must be factored into payload calculations.
Payload = ATM − Tare Weight. It’s the total weight available for water, gas, gear, and everything else carried in or on the van. The higher the payload capacity, the more flexibility there is when loading for a trip.
Lotus caravans are built to conquer the toughest tracks while delivering uncompromised comfort. Features include:
- Bespoke interiors with premium finishes that withstand rugged use
- Advanced off-grid systems for extended, self-sufficient adventures
- Airbag suspension and REDARC electrical systems for ultimate reliability
- Ergonomically designed layouts for comfort on every road and off-grid trail
