An off-road caravan's weight story is told by five numbers: tare weight, ATM, GTM, payload and towball weight. ATM — the maximum loaded weight of the caravan standing on its own wheels — is the figure to match against a tow vehicle's braked towing capacity. Payload, the difference between tare and ATM, is what the owner actually has left for water, gas, luggage and fitted accessories. Get these two checks wrong and a caravan can be legal in the showroom and overweight on the road.

The Five Weight Numbers on a Caravan Specification

Manufacturers publish these ratings on the specification sheet and, in many markets, on a compliance plate fitted to the chassis or drawbar:

• Tare weight. The mass of the caravan as it leaves the factory, without water in the tanks, gas in the cylinders, annex walls or personal effects. Factory tare usually also excludes dealer- or owner-fitted extras such as air conditioning added after weighing.
• ATM (Aggregate Trailer Mass). The maximum permissible weight of the caravan when fully loaded and unhitched, supported by its own wheels and jockey wheel. ATM is a hard limit set by the manufacturer; exceeding it is unsafe and can invalidate insurance and compliance.
• GTM (Gross Trailer Mass). The maximum weight carried through the caravan's own axles and tyres while hitched to the tow vehicle. GTM is always lower than ATM, because part of the load is transferred to the tow vehicle through the coupling.
• Payload. The load allowance between tare and ATM — the weight available for water, gas, food, gear and accessories. Payload equals ATM minus tare on paper, but every option fitted after the tare measurement reduces what is actually left.
• Towball weight (towball mass). The downward force the caravan exerts on the tow vehicle's coupling. It is published for the empty caravan and rises as the van is loaded, which is why manufacturers quote it alongside tare and ATM.

Why Off-Road Caravans Use Up Their Allowances Fast

Off-road builds carry more mass than equivalent highway vans: heavier chassis members, independent trailing-arm suspension, off-road tyres plus a spare, jerry can holders, dual gas cylinders, larger water capacity and bigger battery and solar packages. Each of these is weight that never leaves the caravan. Two practical rules follow.

First, water is heavy — one litre weighs one kilogram, so two 80 litre fresh tanks plus a grey tank add over 200 kg the moment they are filled. Second, payload is consumed in the order things are added: the dealer's options, then the owner's gas bottles and water, then the luggage. A specification that looked generous on paper can leave little margin for a family's gear once the build is complete. Ask how the tare figure was measured and what it excludes before comparing payload across factories.

Matching a Caravan to the Tow Vehicle

The matching rule is simple to state and frequently misapplied: the tow vehicle's braked towing capacity must cover the caravan's ATM when loaded, not its tare weight. Three further limits usually bind tighter than the headline towing figure:

• GCM (Gross Combination Mass). The maximum combined weight of the loaded tow vehicle and the loaded caravan. Even when the caravan's ATM is within the braked limit, the combined figure can be exceeded with passengers, fuel and gear in the vehicle.
• Towbar and ball ratings. The towbar and coupling have their own maximums, often lower than the vehicle's rated towing capacity.
• Vehicle payload. Towball weight counts against the tow vehicle's payload, so a full crew and a heavy caravan can overload the vehicle before the trailer limit is reached.

Terminology differs between markets — ATM, GTM and compliance plates are the norm in Australia and New Zealand, while North American buyers work with GVWR and tongue weight — and registration rules vary by jurisdiction. Confirm which rating system and documentation your destination market expects, and check that the caravan's plates match that standard.

What Dealers Should Verify Before Ordering

A dealer or importer that can explain weights confidently sells more than one that cannot. Before placing an order, confirm the following in writing for each model and configuration you plan to stock:

• The tare weight for the exact build, and a statement of what the figure excludes (gas cylinders, jerry cans, annex walls and similar items are commonly excluded).
• The ATM and, where applicable, GTM ratings as they will appear on the compliance documentation for your market.
• A revised weight estimate for every option you add — air conditioning, diesel heater, upgraded battery and solar, larger water tanks, annex package — since options fitted after the factory tare measurement reduce real payload.
• A full-tank, full-gas check against the payload so your sales team knows the honest load margin to quote customers.
• Axle and tyre ratings consistent with the ATM, so the running gear is not the weak link at maximum load.

Weight and rating data should come from the specification sheet of the exact model, because they vary by model and final configuration. LZM's published caravan specifications list tare, ATM and towball weight by model, which makes a useful first filter when shortlisting which sizes fit the tow vehicles common in your market — the sales team can then provide the weight sheet for the precise build before you commit.

FAQ

Does ATM include a full water tank? Yes. ATM covers the caravan in any loaded condition, including full tanks, full gas cylinders and luggage. Because water weighs one kilogram per litre, a full-tank caravan can sit several hundred kilograms above its empty tare figure.

What does tare weight not include? Tare is the factory-empty mass. It normally excludes water, gas, annex walls, luggage and extras fitted after the tare measurement — the published notes for each model state exactly what is excluded.

Is payload simply ATM minus tare? That is the arithmetic starting point, but the practical payload shrinks as options and consumables are added. Compare payload using the real build, not the bare factory figure.

Can a typical full-size 4WD tow a 3,000–3,500 kg ATM off-road caravan? It depends on that specific vehicle's braked towing capacity, GCM and towbar rating — many are rated near the upper end, but each of the three limits must be met, and local towing rules apply. Verify against the vehicle manufacturer's documentation for the exact model and year.

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