Towing a caravan isn’t just about hitching up and hitting the road — it requires a clear understanding of the weight ratings that keep your setup safe and legal. One of the most important figures is the ATM, or Aggregate Trailer Mass. For anyone comparing specs, checking compliance plates, or planning a trip, knowing what ATM means on a caravan helps avoid costly mistakes and ensures peace of mind. Caravans in Heatherbrae are built with a range of weight profiles that suit both novice and experienced travellers alike.
What is ATM on a caravan?
ATM stands for Aggregate Trailer Mass. It refers to the maximum allowable weight of a fully loaded caravan when it is not connected to a tow vehicle. This figure includes the caravan’s tare weight (the weight as delivered from the manufacturer), plus the payload — everything you load into it, such as food, water, gas, luggage, and equipment. It also includes any aftermarket additions like bike racks, toolboxes, or solar panels. The ATM is stamped on the compliance plate and must never be exceeded. Doing so could make your setup illegal, dangerous, and potentially uninsurable.
The ATM figure is critical because it directly affects what your tow vehicle needs to be capable of. You must ensure your vehicle’s towing capacity meets or exceeds the ATM of the caravan — not just its empty weight. This is where many first-time buyers get caught out, especially with heavier off-road or full-height vans.
Why does ATM matter when towing?
ATM isn’t just a technicality — it’s a key safety measure. Exceeding your caravan’s ATM can compromise braking performance, stress your suspension, and make your van more prone to sway. It also increases the risk of insurance claims being denied in the event of an accident.
If you’re new to towing or travelling long distances, understanding ATM helps you pack smarter and tow safer. It forces you to think carefully about what you really need to bring, especially when combined with water, gas, and camping gear. Knowing your van’s ATM also helps when using weighbridges, calculating payload, or discussing ATM upgrades with a certified engineer.
You’ll find more guidance in our article on how to tow a caravan, which breaks down tips for weight distribution and towing technique.
How is ATM different from GTM and GVM?
ATM is often confused with GTM (Gross Trailer Mass) and GVM (Gross Vehicle Mass), but they’re different things. ATM is the total maximum loaded weight of the caravan when unhitched — it includes everything onboard. GTM refers to the maximum weight of the caravan when connected to the tow vehicle, meaning it excludes the portion of weight transferred to the vehicle’s tow ball.
GVM, on the other hand, applies to the towing vehicle. It refers to the maximum allowable weight of the vehicle including its passengers, fuel, and cargo. For safe towing, you need to consider all three figures: the ATM of the caravan, the GVM of your tow vehicle, and how they interact when hitched together.
This is covered in more depth in our article on how to install a diesel heater in a caravan, which touches on installation without exceeding load limits.
Where do I find the ATM of my caravan?
You’ll find your caravan’s ATM listed on its compliance plate, usually located on the drawbar, in the front boot, or inside the main entry door. This plate includes several critical weight figures, including:
- Tare weight (empty weight as manufactured)
- ATM (maximum loaded weight unhitched)
- GTM (maximum loaded weight hitched)
- VIN number
If you’ve purchased a second-hand caravan, keep in mind that the actual weight might differ from what’s on the plate — especially if modifications have been made. Additions like solar systems, toolboxes, air conditioning units, or even a different awning can increase the van’s tare and reduce your available payload. To get an accurate, real-world reading, take the van (empty and loaded) to a certified weighbridge.
What happens if I exceed the ATM?
Exceeding your caravan’s ATM is not only illegal — it can be dangerous. Overloading puts stress on the chassis, axles, brakes, and tyres. It can make your caravan harder to handle, more likely to sway, and slower to stop. Police can issue fines and defect notices if your caravan is found to be overweight, and more importantly, insurers may reject claims if your rig exceeds its rated limits.
If you consistently find yourself pushing the payload limit, you might need to rethink what you pack or consider an ATM upgrade through a licensed engineer. You’ll also want to verify whether your tow vehicle can handle the load — and don’t forget to factor in water and gas. Learn more in our post on how much it costs to travel around Australia in a caravan, where weight plays a big role in running costs.
FAQs
What does tare weight mean on a caravan?
Tare weight is the base weight of a caravan as it leaves the factory — with no personal belongings, water, gas, or aftermarket modifications. It includes factory-fitted features and accessories but doesn’t allow for things like solar panels, extra batteries, or bike racks added after purchase. Tare weight is critical because it helps determine your available payload, which is the difference between tare and ATM. You’ll find it listed on your caravan’s compliance plate. Keep in mind that the tare listed might not reflect real-world conditions if the van has been modified since manufacture. If in doubt, weigh your van when empty using a public weighbridge.
How is ATM different from GCM?
ATM (Aggregate Trailer Mass) refers to your caravan’s maximum loaded weight when unhitched. GCM (Gross Combination Mass), on the other hand, refers to the maximum combined weight of your tow vehicle and caravan — fully loaded — as set by the tow vehicle’s manufacturer. So while ATM is about the van’s limit, GCM is about the combined total weight that your vehicle is legally allowed to move. Both figures matter when planning safe and legal towing. If you exceed your vehicle’s GCM, you may face serious legal, mechanical, and insurance risks — even if your caravan itself is within its ATM limit.
Can I increase my caravan’s ATM?
Yes — in many cases you can increase your caravan’s ATM, but it must be done properly and legally through a certified upgrade process. This might involve structural changes such as reinforcing the chassis, upgrading the suspension or brakes, or installing heavier-duty axles. A licensed engineer will need to assess and certify the modifications, after which you’ll be issued with an updated compliance plate. Keep in mind that increasing your ATM doesn’t raise your tow vehicle’s towing limit — that’s fixed by the vehicle’s manufacturer. Also, not all caravans are suitable for upgrades, so it’s best to consult both your manufacturer and an engineer before proceeding.
What happens if I exceed the tow vehicle’s limits?
If you exceed your tow vehicle’s rated towing capacity — or any of its axle, ball weight, or GVM limits — you risk serious consequences. This includes mechanical failure, reduced braking performance, and compromised safety on the road. It can also void your vehicle’s warranty and make you liable in the event of an accident. Police can issue fines and, in some states, impound the vehicle if it’s deemed unroadworthy. Always cross-check the ATM of your caravan with your tow vehicle’s maximum towing capacity, and consider the overall weight (GCM) as well. Staying within limits keeps your trip legal, safe, and stress-free.
Does ATM include water and gas?
Yes — ATM includes everything loaded onto the caravan when it’s fully packed, including water in the tanks, gas bottles, food, clothing, and gear. It also includes permanent fixtures like toolboxes, solar panels, and batteries. This means if you travel with full water tanks and gas bottles, that weight is part of the ATM. It’s easy to miscalculate how quickly weight adds up, especially on long trips. Two 9kg gas bottles, a full water tank, and camping gear alone can push you close to your limit. That’s why weighbridges are essential tools for staying within legal and safe limits.
Understanding caravan weight limits
Knowing what ATM means — and how it fits into the broader towing picture — is one of the most important steps toward safe, legal, and enjoyable caravan travel. By understanding the numbers, checking your compliance plate, and weighing your setup before big trips, you can avoid nasty surprises and keep your caravan adventures running smoothly.
Start your journey with confidence — visit 7th Street Caravans or give our team a call on 02 4012 6009 for friendly, local advice.