If you’re going to be travelling around with a caravan it’s absolutely essential that you know your caravan towing weights.
With caravan towing weights, you need to know what your car can legally tow, as well as how much payload (accessories, gear and “stuff”) you can add to your car and caravan. The most important terms to learn about are GVM, ATM, GCM and Tow Ball Weight, among a few others.
The ramifications of being overloaded include voiding your insurance, having an unstable set up and a big increase in your crash risk.
Here we’ll simplify what each towing term means and how to calculate your towing weights for yourself.
To get an idea of what to expect with caravan weights, check out my posts on average caravan weights and the full list of Jayco weights & lengths.
Once you’ve got a handle on the weight terms and meanings, use the calculator below to work out your own towing weights.
This post may contain affiliate links or mention our own products, please see our full disclosure policy here.
Why Do You Need to Know Your Caravan Towing Weights?
Learning all about caravan towing weights may feel overwhelming, insignificant or just plain boring. But the reality is, it’s one of the most important things you need to know as a caravanner.
If you’re not sure if your car can even tow a caravan, or if you’ll need to upgrade, check out the following article before going any further.
Here are some reasons to get serious about knowing your Caravan Towing Weights:
- Being overweight is illegal
- Too much weight puts strain on your chassis & running gear
- An overweight van can cause the ‘Death Wobbles’ due to instability
- An overweight van will not be covered by insurance
- Department of Transport and Main Roads can fine you and ground your caravan (meaning you either need to remove weight or a tow truck will be called to take it away)
Caravan Towing Weights Explained
Caravan Towing Weights Summary
| CARAVAN TOWING WEIGHT TERMS |
|---|
| KERB WEIGHT = Weight of Empty Vehicle + Oil & Fluids + Full Tank of Fuel |
| VEHICLE TARE WEIGHT = Weight of Empty Vehicle + Oil & Fluids + 10L Fuel |
| GVM = Maximum Allowable Weight of Vehicle |
| CARAVAN TARE WEIGHT = Weight of Empty Caravan + Only Factory-fitted Accessories |
| ATM = Maximum Allowable Weight of Caravan |
| GCM = Maximum Allowable Weight of Car + Caravan |
| TBW = Approx. 10% of ATM (cannot exceed 350kg) |
| GTM = ATM – TBW |
| VEHICLE PAYLOAD = GVM – Tare Weight |
| CARAVAN PAYLOAD = ATM – Tare Weight |
| TOWING CAPACITY = Maximum Allowable Weight the Vehicle Can Tow |
Kerb Weight
The Kerb Weight of a vehicle is the weight of the car, oil and fluids, plus a full tank of fuel. It does NOT include luggage, driver, passengers or accessories (e.g. bull bar, tow bar, roof racks etc.). Consider it as how you’d be driving the car away from the kerb at a dealership.
| KERB WEIGHT = Weight of Empty Vehicle + Oil & Fluids + Full tank of fuel |
Vehicle Tare Weight
The Vehicle Tare Weight is the weight of an empty vehicle with all of its fluids, but only 10 litres of fuel in the tank. This is how much the car weighs at manufacturer specification with all fluids and only 10 litres of fuel, but no payload (i.e. no driver, passengers, luggage etc.).
| VEHICLE TARE WEIGHT = Weight of Empty Vehicle + Oil & Fluids + 10L Fuel |
Gross Vehicle Mass (GVM)
The Gross Vehicle Mass (GVM) is the maximum allowable weight of the vehicle including passengers, luggage, accessories and Tow Ball Weight. The GVM is set by the manufacturer, which states the maximum weight the vehicle can be at any given time and cannot be exceeded.
| GVM = Maximum Allowable Weight of Vehicle |
Caravan Tare Weight
The caravan tare weight is the weight of the caravan, including any accessories fitted at the time of the build, but with empty water tanks, empty gas cylinders. This is the weight of the caravan as you’d be driving it out of the factory.
NOTE: Any accessories that were included in the caravan build, will be included in the Caravan Tare Weight. However, any accessories that you fit after that point will come out of the payload.
| CARAVAN TARE WEIGHT = Weight of Empty Caravan + Only Factory-fitted Accessories |
Aggregate Trailer Mass (ATM)
The caravan ATM (Aggregate Trailer Mass) is the maximum allowable weight of the caravan as set by the manufacturer. It’s much like the car GVM, but this is the trailer version.
So, the ATM is the maximum weight that the caravan is allowed to be when fully loaded and unhitched from the vehicle. This weight includes all accessories, luggage, full water tanks, gas bottles, tool boxes, bikes etc.
| ATM = Maximum Allowable Weight of Caravan |
Gross Combination Mass (GCM)
The Gross Combination Mass (GCM) is the maximum allowable weight of your car and caravan combined. The GCM figure is set by the manufacturer of your vehicle and it can’t be changed.
This total combined mass of both the car and trailer includes all gear and luggage, accessories, driver and passengers, fuel, water etc.
| GCM = Maximum Allowable Weight of Car + Caravan |
Tow Ball Weight (TBW)
There are many terms you may come across for Tow Ball Weight, such as Tow Ball Download, Ball Load and Hitch Weight.
Tow Ball Weight is the amount of weight the fully loaded caravan puts on the tow bar of the tow vehicle. Keep in mind that the TBW will change every time you add, subtract or shift payload in your caravan.
The accepted Tow Ball Weight in Australia is generally around 10% of your ATM or a maximum of 350kg, whichever is lower.
Essentially that 10% of weight comes off your caravan and onto the back of the car. So, that Tow Ball Weight will effectively transfer onto your vehicle’s GVM as its part of the car’s payload.
Here are some tow ball weight reduction tips if you find that yours if over its limit.
| TBW = Approx. 10% of ATM |
Gross Trailer Mass (GTM)
The Gross Trailer Mass (GTM) is the weight of a fully loaded caravan when it’s hitched up to the tow vehicle. It’s the maximum axle load that your trailer is designed to carry, as specified by the caravan manufacturer.
To work it out, you take the maximum allowable weight of the caravan (ATM) and minus the tow ball weight (TBW). The reason we take off the TBW is because the car is now carrying that weight, which was once resting on the jockey wheel.
| GTM = ATM – TBW |
Payload
The Payload or ‘loading weight’ is the combined weight of all items that you can add or load into your car and caravan. This is anything above the Tare Weight, which was specified by the manufacturer.
Think of Payload as your available carrying capacity (i.e. how much “stuff” you can load into it).
| VEHICLE PAYLOAD = GVM – Vehicle Tare Weight CARAVAN PAYLOAD = ATM – Caravan Tare Weight |
Payload Item Examples:
- Luggage
- Passengers
- Water
- Gas
- Bikes, kayaks, recovery gear
- Food and cooking gear
- Clothing and linen
- Non-standard accessories (bull bar, tow bar, side steps)
- Modifications and additions (annex, TVs, solar, batteries)
- Tow ball weight
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Towing Capacity
The Towing Capacity is the maximum weight that your vehicle can legally tow, also known as ‘Maximum Braked Towing Limit.’
It’s the maximum trailer weight that the vehicle can tow if the caravan has its own braking system (which most modern ones do). Braked Towing Capacities for Australian cars generally range from 2300kg – 3500kg, depending on the chassis, body construction and engine.
If you’re buying an older caravan or smaller camper without its own brakes, you’ll need to know the ‘Maximum Unbraked Towing Limit’ of your car. By law in Australia, the Unbraked Towing Capacity of a car is capped at 750kg.
| TOWING CAPACITY = Maximum Allowable Weight the Vehicle Can Tow |
Where to Find Your Towing Specifications
To work out your various caravan towing weights, you’re going to need to locate the manufacturer’s specifications. Some of the other figures you will need to work out yourself, which we will go through next.
You should find all of the information you need on your compliance (VIN) plate. These can be located just inside the door of your caravan. Other places it may be hiding is inside the front boot or on the drawbar.
Sometimes there may be an additional modification tag if there have been any certified upgrades. We had our ATM upgraded by an extra 100kg, which was as high as we could go without having to change out the entire suspension. The mod tag for the upgrade was located inside the front boot, while the VIN Plate was just inside the caravan entry door.
If you can’t find the VIN Plate, have a look at the registration papers and the Owner’s Manual if you’ve got it.
For the Tow Bar, you may have a specification plate attached to it. Otherwise, you’ll need to contact the manufacturer or installer for more information.
When it comes to lengths, here are the 6 ways to measure your caravan’s length.
How to Work Out Caravan Towing Weights
When you’re ready to find out your own caravan’s weights, here’s the full Step-by-step Instructions for Weighing a Caravan.
Caravan Payload
Remember, the payload is the capacity of how much “stuff” you can load into the caravan (water, annex walls, clothing, food, cooking items, extra solar gear etc.)
How to work out caravan payload:
- Take the caravan Tare Weight
- Take the caravan ATM
- Minus the Tare Weight from the ATM
- This figure is your caravan Payload (ATM – Tare = Payload)
| CARAVAN PAYLOAD EXAMPLE |
|---|
| Caravan Tare is 2,500 kg Caravan ATM is 3,000 kg 3,000 kg – 2,500 kg = 500 kg Payload |
Vehicle Payload
The Tow Vehicle Payload is the weight you can allow for passengers, luggage, roof racks, full tank of fuel, bull bar and any additional accessories. You will also need to include the tow ball download weight as part of the vehicle’s payload when towing.
How to work out tow vehicle payload:
- Take the car Tare Weight
- Take the car GVM
- Minus the Tare Weight from the GVM
- This figure is your car Payload (GVM – Tare = Payload)
| VEHICLE PAYLOAD EXAMPLE |
|---|
| Car GVM is 3,000 kg Car Tare is 2,200 kg 3,000 kg – 2,200 kg = 800 kg Payload |
Or, you can easily work out your payload allowances for both the car and the caravan using the calculator below.
Tow Ball Download
To work out how much weight the caravan is putting on the tow ball of the car, there are a few options. Check out the full post to see the step-by-step process for all 3 ways to measure your Tow Ball Weight.
Firstly, you can get yourself a set of Ball Weight Scales and weigh it yourself at home. They’re really easy to use with the added benefit of being to able to find out your adjusted ball weight after adding/ removing water and gear from the van.
How to work out Tow Ball Download with Ball Weight Scales:
- Chock the wheels
- Wind up the jockey wheel
- Sit the Ball Weight Scale under the coupling
- Wind down the jockey wheel
- Read the weight on the scale.
| BALL WEIGHT SCALES | |
|---|---|
| ➤ eBay | From $47 AUD • Ball Weight Scales → |
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Or secondly, you can head to a local Public Weighbridge and get your weights there (the steps for that are below).
How to work out Tow Ball Download at a Weighbridge:
- Hitch up your caravan and drive to a Public Weighbridge
- Drive only the 4 car wheels onto the scales
- Write down the weight (Weight A) – this is the car’s weight + tow ball weight
- Unhitch your van off the scales
- Drive the car back onto the scales
- Write down the weight (Weight B) – this is the car’s standalone weight
- Tow Ball Download = Weight A (car weight) – Weight B (car weight with tow ball weight)
| WEIGHBRIDGE TBW EXAMPLE |
|---|
| My car with the caravan hitched up weighs 2,300 kg. The weight of the car without the van is 2,100 kg. Therefore the Tow Ball Weight is 200 kg. |
GTM (Gross Trailer Mass)
The GTM is basically the fully-loaded weight of the caravan while hitched up to the tow vehicle. This is basically the maximum caravan weight (ATM) minus the Tow Ball Weight, because that Tow Ball Weight gets transferred to the car’s weight when you’re hitched up.
How to work out GTM (Gross Trailer Mass)
- Take the caravan ATM
- Take the Tow Ball Weight
- Minus the Tow Ball Weight from the ATM
- This figure is your Gross Trailer Mass (ATM – TBW = GTM)
| GTM EXAMPLE |
|---|
| Caravan ATM is 3,000 kg Tow Ball Weight is 200 kg 3,000 kg – 200 kg = 2,800 kg GTM |
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Caravan Towing Weight FAQs
GVM is the Gross Vehicle Mass, meaning the maximum allowable weight that your vehicle can be, which is set by the car manufacturer. GVM is not the caravan’s weight, but rather, the weight of the tow vehicle.
No, GVM is the heaviest weight that your tow vehicle is allowed to be, while the towing capacity is the maximum weight (set by the vehicle manufacturer) that your tow vehicle is allowed to tow.
The ATM weight is the maximum allowable weight of the caravan or trailer when it’s unhitched from the tow vehicle (including all luggage, accessories, fluid tanks etc.).
GVM = Maximum allowable weight of the vehicle (including luggage, passengers & tow ball weight).
ATM = Maximum allowable weight of the caravan when unhitched from the vehicle (including luggage, full water tanks etc.).
GVM is the maximum allowable weight of the vehicle when fully loaded (including tow ball weight). Tare weight is the empty weight of the vehicle or trailer (before adding accessories, passengers, fuel, luggage, water etc.).
GTM or Gross Trailer Mass is the weight of a fully loaded caravan, hitched up to the tow vehicle. To work it out, you take your ATM (max allowed weight of caravan) and subtract the tow ball weight (because now that weight has shifted off the van and onto the car).
ATM = Maximum allowable weight of the trailer when unhitched from the vehicle (including luggage, full water tanks etc.).
GTM = Weight of a fully loaded trailer when hitched up to the vehicle.
The caravan Tare Weight or Tare Mass is the weight of the caravan before adding accessories, luggage, water etc. This is essentially the weight of the caravan as you pick it up from the dealer before you’ve modified it and added your “stuff.”
As the ATM is the maximum allowable weight that the caravan can be when fully loaded, it cannot exceed your vehicle’s legal towing capacity.
The tare weight is always the empty weight before adding anything into the vehicle or trailer.
Yes, when the caravan is hitched up to the tow vehicle, the tow ball weight is then transferred onto the vehicle and now must be included in the vehicle’s Pay Load capacity.
Should You Tow With Full Water Tanks?
Now that you’ve got your caravan and tow vehicle weights sorted, you may be wondering if it’s a good idea to actually travel with full water tanks or not.
Maybe you can see now that you just don’t have the payload capacity to allow for full water tanks, which makes the decision pretty clear for you.
But, if you plan of doing a lot of Free Camping, you’ll definitely want to be able to cruise around with water in your tanks.
It’s been proven that full water tanks improve stability and can help with load distribution and tow ball weight. But, we can’t discount the fact that carrying water deducts from the payload you have available for other items, plus extra weight = extra fuel consumption.
Remember, water tanks should be FULL or EMPTY, never in between.
Half-full tanks create ‘water slosh,’ which can cause trailer sway.
Have a read of the full article below to find out what’s best for you.
CARAVAN ACCESSORIES
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What seems to be missed here is the maximum rear axle weight from the manufacturer of the tow vehicle. It is good to keep your weight under your GVM but when you have added the tow ball weight you also get a percentage of something like a 6% transfer of weight from the front axle onto the rear axle and this puts many tow wagons over their maximum rear axle load. This is most important if you are under warranty or insurance policy.
Thanks for adding that in!
As ball weight is weighed disconnected from the tug it is that weight always. While a WDH may shift some weight forward and back to the van the Actual ball weight does not alter.EG. You cannot have a ballweight that exceeds tugs capacity and try and lessen it with a WDH as if it gets weighed it will be what it is.
I have a 4WD ute with 5700kg GCM. I lose weight on my front axel about 100kg so that brings me back to 5600kg GCM. Tow ball weight seams to be counted on the towing vehicle and the caravan, so if you have 200kg tow ball weight that means you would lose another 200kg bringing my GCM back to 5400kg.
If you are weighted by the heavies do they only weight each axel or do they weight tow ball weight as well. If you have load bars on this would change your load on your front axel of the towing vehicle and axels on the caravan. Dose this take weight off your tow ball.
That’s correct, the tow ball weight actually comes off your caravan weight and gets added onto your tow vehicle’s weight. So, the 200kg tow ball weight would be subtracted from your ATM (trailer mass) and added on to your GVM (vehicle mass). I’m not entirely sure how the Dpt Transport weigh the caravans as I’ve never been pulled over by them (touch wood). I’m guessing they’d weigh tow ball weight as well, since it’s a pretty simple scale to carry with them. Particularly for those vehicles that look way too heavy in the rear. So, the weight distribution bars do shift some of that rear weight to the front axles, which could alter your tow ball weight. You’d have to play around with it all to ‘massage’ the figures to your liking.
Hi There, I weigh caravans and vehicles here in WA. The fitting of a WDH does not alter the towball weight and transfers little weight back to the caravan but very effective in moving weight to the tow vehicles front axle. That is the only reason I recommend use of a WDH. Cheers Mark
Thanks for clarifying for us Mark.