What is ATM on a caravan?
The most your loaded caravan is allowed to weigh, set by its manufacturer and stamped on the van.
ATM is the most your caravan is allowed to weigh when it is fully loaded and standing on its own wheels, unhitched from the car. The manufacturer sets it and it is stamped on the van's compliance plate. Your loaded van must never go over it, however strong the tow car is.
Also called Aggregate Trailer Mass.
- Set by - the van's manufacturer, from its chassis, axles and suspension
- Marked on - the van's compliance plate, beside the GTM (Gross Trailer Mass)
- Compare with - your car's braked towing capacity when you shortlist vans
What ATM counts
ATM caps the whole loaded van, as it stands unhitched on its own wheels and jockey wheel.
It counts the empty van plus everything in it: water, gas, food, bedding, tools and the annexe.
The weight that presses on your tow ball after you hitch up is part of the ATM.
That is why ATM is the figure to hold against the car's towing capacity.
ATM across the caravans we list
Among the caravan ranges we list, using each range's published figure, the middle ATM is about 3,000kg.
Half are rated above that figure and half below it.
The middle payload, worked out as ATM minus tare for each van, is about 630kg.
Where to find the ATM
The ATM is stamped on the van's compliance plate, with the GTM and, on current builds, the tare.
The plate carries the rating for that exact van, so trust it over a brochure figure.
Where the plate sits varies by maker and model.
Our compliance plate guide lists the common places to look.
How ATM shapes the car you need
Start a shortlist by comparing each van's ATM with your car's braked towing capacity.
A common first step is to cross off any van whose ATM is above the car's rating.
Towing capacity is one of several limits on the car.
GVM (Gross Vehicle Mass), GCM (Gross Combination Mass), the towball limit and the towbar and towball ratings all apply at the same time.
Whichever one you reach first sets what you can tow.
How water eats into an ATM
These figures are made up and rounded to keep the sums simple.
Take a van with a 3,000kg ATM and a 2,400kg tare.
Its payload is 600kg, the most you can add before the van is over its ATM.
Fill two 95 litre water tanks and you have used 190kg of that, because a litre of water weighs about a kilogram.
That leaves 410kg for gas, food, bedding and gear.
Common mistakes with ATM
- Planning on tare - the van you tow is loaded, so plan against the ATM
- Forgetting water - full tanks are often the heaviest thing you add
- Trusting the brochure - the plate on the van you buy holds its rating
- Guessing - a weighbridge ticket shows what the loaded van really weighs