When you set off on a trip with your caravan or camper trailer in-tow the most important thing in the world is the safety of your family. Many people choose to ignore the guidelines for safe caravan or trailer towing and sometimes this leads to horrific accidents. If you overload your caravan/camper or towing vehicle you are putting yourself, your family and other road users at risk. So make sure you follow the guidelines and laws around towing that apply to the vehicle you are towing and your towing vehicle.

Fines

Fines for unsafe, overloaded vehicles and tow vehicles.

There are heavy penalties for driving an unsafe vehicle or for not having the right towing set up.

Insurance

If you have an accident and your caravan/camper or tow vehicle is deemed to have been unsafe it is very likely your insurance will be void.

So, keep your family safe, avoid fines and stay insured by keeping your caravan loads and towing setup within safe, legal limits.

Here is a handy guide to help you understand towing weights and loads.
Caravan Towing Weights & What They Mean

If you’re new to the world of caravanning, getting to grips with the numerous references to towing weights & capacity can be quite daunting.
You might find yourself asking “what does ATM mean?” or “what is a Tare Weight”.

So Explorer Caravan Sales have put together a simple guide to help you understand the various aspects of towing weights, what they mean.
Ensuring you have the right set up and are not exceeding the legal weight limits will mean safer and legal towing.

Check Weights & Vehicle Towing Capacity Before You Buy

When you’re looking for a new caravan you’ll need to be aware of what your vehicle’s towing capacity is.
This can be confusing. There are a number of abbreviations or ‘acronyms” used to refer to various categories of towing weight.
You’ll need to be familiar with these terms, what they mean and how they fit into any calculation regarding the weight of your caravan, the towing capacity of your vehicle and the combined weight of your vehicle and caravan.
Here’s a simple guide to towing weights and their meanings.

TARE

“The weight of the caravan with nothing in it or “unladen” weight.

This is not an acronym. Tare is taken from the Latin word “Tara” which means to deduct.
So take the weight of any container or packet, remove the contents and the weight of the empty container – in this case your caravan – is the Tare weight.

So Tare is the weight of your caravan as manufactured.

This means that the caravan has not been loaded up with any belongings. No clothes, cutlery, water in the tanks or beer in the fridge.

Payload

“Payload is the weight of the contents you put into your caravan”

Everything you load into your caravan before you set off on your journey contributes to your payload. This also represents the difference between the caravans ATM and Tare.

Payload + Tare = ATM (Aggregate Trailer Mass)

ATM (Aggregate Trailer Mass)

“The weight of the caravan fully loaded when not hooked up to the car”

Aggregate means to collect together or sum – not to be confused with average.So ATM is the weight of your caravan plus (Payload) the weight of anything you put inside the caravan.

ATM includes your annexe, water in tanks, food, clothes, cutlery and gas and other goodies.
This is the most important weight to take into account when considering your vehicle’s towing capacity.

ATM Rating Of Your Caravan

Each caravan has a different ATM Rating

The ATM rating is displayed on the caravan’s VIN Plate. It is the maximum amount of weight that should be loaded into your RV, as specified by the manufacturer.

Tow Ball Weight or Tow Ball Mass

“The amount of weight on your vehicles tow ball”

This is the amount of your caravan’s weight placed on your vehicle’s tow ball, when the caravan is hitched up and the jockey will is raised.This is the load placed on a vehicle’s tow ball. Difference between ATM and GTM. You’ll need to make sure that this does not exceed the amount of weight that can be placed on your towing vehicles tow ball.

How do you measure Tow ball weight?

Measuring tow ball weight can actually be done pretty easily. You can buy dedicated tow ball weight scales like the Milenco – Precision Calibrated Ball Weight Gauge – from any decent auto shop, or caravan supplies company.

Here’s a short video from out friends at Caravan World

Alternatively you can use one or two bathroom scales with a block of wood on top of them.

Simply load your RV up as you would normally for a trip away including full water tanks. Position it on smooth, level ground. Put the tow ball scales under the tow ball and lower the jockey wheel so that all of the weight is sitting on the tow ball scales.

It’s important to think about the height that your trailer sits at on your vehicle. if it’s significantly different you will get a different reading.

Use A Weigh Bridge

Alternatively, you can do this at a weigh bridge fairly easily, by weighing the 4WD only when the trailer is attached (so just have the car on the weighbridge), then detach the trailer and weigh just the vehicle. The difference is the weight the trailer is applying to the tow ball.

GTM (Gross Trailer Mass)

“This is the weight of a caravan fully loaded and hitched up to a vehicle.”

This will always be a lower weight than the ATM of your caravan.Remember these figures will be different every time you go away as they are dependent on what you have loaded into your caravan. More payload means a higher ATM and hence a higher GTM.

You can work out GTM in a couple of ways.

1. Subtract the tow ball weight from your vehicle’s ATM.
2. Hitch your caravan up to your vehicle, go to weighbridge and – with your caravan still hitched to your tow vehicle weigh just your caravan.

Now on to your towing vehicle

Car Tare weight

“The weight of your car without anything in it”

Your car’s Tare weight is how much it weighs with no people or belongings inside it. It includes the weight of liquid containers filler, except for fuel, which is 10 litres only. It also includes all options and standard equipment that are fitted to the vehicle.

GVM (Gross Vehicle Mass)

“The weight of a fully loaded motor vehicle”

The weight of a fully loaded motor vehicle, specified by the manufacturer of the vehicle. This includes people and belongings.The vehicles’ equivalent of the caravan’s ATM.

Your Towing Vehicle & Caravan combined

GCM/GCVM – Gross Combined Mass

“This is the combined weight of your caravan and vehicle hitched together and fully loaded”

So you have two loaded vehicles, your caravan or trailer and your towing vehicle. Each has a maximum allowable weight – ATM for your caravan and GVM for your vehicle.Adding these together gives your maximum GCM.

WARNING

Do not load your vehicle and caravan/camper to their maximum allowable capacity.

Remember that the more you load into your RV the more weight there is on your towing vehicles tow ball. This weight adds to your vehicles’ GVM and could mean you exceed the safe and roadworthy limit for your vehicle.

It is always advisable to carry less weight than the maximum allowed.

Figuring out the weight of your caravan

Sometimes the weight on the VIN plate can be wrong, the only sure way to be sure is to weigh your caravan or camper

The only sure way to know what your RV weighs is to use something like a weighbridge. This goes for both unloaded and loaded, but as mentioned before, it is best to use the ATM when figuring out what your vehicle will need to tow.

Click here for a list of weighbridges in your state

Find my nearest Weighbridge

If you don’t have access to a weigh bridge and are unsure about the overall weight of the caravan, you can try to calculate the weight of your payload yourself. This would mean weighing all of the gear you’ll be taking with you on your trip, AND adding the weight from full water tanks and gas bottles.

Your vehicles ATM & TARE are on the VIN plate

What is a VIN plate?

VIN stands for Vehicle identification number and refers to a unique number attributed by the manufacturer to your vehicle or RV.

The VIN plate, or compliance plate, is a small metal plate fixed to every caravan that contains the caravan’s VIN number, towing weights and other useful information. It will also detail who the manufacturer was, what model the RV is, the date that it was manufactured and TARE & ATM.

The weights displayed on the VIN plate will be specific to your caravan which will have been weighed at the factory. You’ll also find that the VIN plate contains other helpful measurements and information like wheel size and recommended inflation.

Where is my Caravan’s VIN Plate?

Where you’ll find the VIN plate depends on the make of the caravan. Often it can be found in the tunnel boot, front boot or somewhere on the A-Frame. Make sure you ask your dealer where it is on your model.

How much can my vehicle tow?

Every vehicle will have a different towing capacity. If you are thinking of buying a caravan or camper, it is a good idea to consider what kind of caravan you would like and what kind of towing capacity you will need.
Check this against your current vehicles towing capacity – is it up to scratch?

The vehicle manufacturer will give you a figure for both braked and unbraked towing capacity. This refers to whether the caravan or camper you’re towing has its own brakes or not.
The braked towing capacity will always be higher. When towing a caravan or camper trailer you’ll most likely be using the braked figure.

It is also important to note that some manufacturers may include specific conditions that should be adhered to when towing their vehicle.

Here is a quick guide that compares towing capacity to the average weights of caravans. It is by no means definitive and average weights for different kinds of caravans will vary between manufacturers. It is intended as a guide for a starting point. Caravans of the same model and manufacturer may differ due to different layouts being offered in a series and extras included in the build.