Short answer

ATM, GTM and Tare are weight limits that determine how much your caravan can safely carry and tow. Exceeding them can affect handling, braking, durability, insurance, and legal compliance - especially on rough or corrugated roads.

Understanding these numbers is essential for anyone towing an off-road or hybrid caravan.

What is Tare weight?

Tare is the empty weight of the caravan as it leaves the manufacturer.

It usually includes:

• the base caravan

• standard fittings

• empty water tanks

• empty gas bottles

It usually does not include:

• personal gear

• food

• water

• optional accessories added later

Why it matters:

Tare is the starting point for working out how much weight you can safely add to your caravan.

What is ATM (Aggregate Trailer Mass)?

ATM is the maximum total weight the caravan is legally allowed to weigh when fully loaded and not connected to the tow vehicle.

This includes:

• the caravan itself

• all water

• all gear

• accessories

• everything carried inside or on the caravan

Why it matters:

If your loaded caravan exceeds its ATM, it may:

• be unsafe to tow

• exceed chassis or suspension limits

• cause insurance or compliance issues

What is GTM (Gross Trailer Mass)?

GTM is the weight of the caravan when it is hitched to the tow vehicle, measured at the wheels.

In simple terms:

GTM = ATM minus tow ball weight

Why it matters:

GTM relates directly to:

• axle load

• suspension stress

• tyre ratings

• long-term durability on rough roads

On corrugated tracks, excessive GTM can significantly increase wear and fatigue.

Why these weights matter more off-road

Off-road and remote touring places far higher stress on a caravan than sealed roads.

Key reasons:

• corrugations amplify loads

• constant vibration stresses suspension and mounts

• water, fuel and recovery gear add significant weight

• poor weight distribution increases chassis fatigue

Understanding and respecting ATM and GTM helps:

• reduce structural stress

• improve towing stability

• protect suspension and running gear

• extend the life of your caravan

A simple real-world example

If a caravan has:

• ATM: 3,500 kg

• Tow ball weight: 350 kg

Then:

• GTM: 3,150 kg

If too much weight is added behind the axles, both handling and durability can suffer - even if the ATM isn’t exceeded.

What caravan owners should do

• Know your caravan’s Tare, ATM and GTM

• Load heavier items low and close to the axles

• Be mindful of water and accessory weights

• Recheck weights after adding accessories or packing for long trips

For safer setup and maintenance when packing gear or checking load distribution, consider tools like the Portable Telescopic Ladder with Carry Bag - compact and stable access makes loading roof racks and redistributing weight easier.

Having a reliable off-road jack on hand can also help if you need to lift the caravan to adjust placement, check weight on individual wheels, or support the trailer while adjusting gear.

Ask questions if numbers are unclear.