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Camper Trailer Weights and Towing capacity Jargon explained

When you first start searching for a new camper trailer, you may not be familiar with the industry lingo and jargon, and it can get pretty confusing. The following information is essential in choosing the appropriate vehicle/camper trailer combination. That is, a camper trailer that meets your family’s needs while also being able to be legally and safely towed by your current vehicle. 

Let’s say the towing capacity of your vehicle says it has a braked capacity of 3,000 kg. You might think, wow, I can just buy the best camper I can afford with all the bells and whistles. This might be an option. However, there is more to consider – and if you get it wrong you may not be able to take anything else with you, not even your children. Let’s get back to basics and define some key weight terminology to help demystify the selection process so you know how much you will be able to handle. So – How much can you really tow, what’s a GTM and GVM and more? 

*note: this information is broad in nature. If you are unsure of any of your weight limits, please contact the manufacturer of the vehicle to confirm your limits. Towing a trailer over you capacity is not only illegal – but also incredibly dangerous – so make sure you get this right!

 

First, Let's define some weight terminology

Payload

Payload is the vehicle’s carrying capacity, calculated by subtracting KW from GVM. The maximum weight of extras that you can pack in your vehicle is the total weight of passengers, luggage, and tow-ball load.

Towing Capacity

This is dictated by the manufacturer, who takes into account factors including the design of the vehicle and the weight on the rear axle as well as the capacity of the tires to determine how heavy a trailer will be on a vehicle. Vehicle manufacturers equate towing capacity to ATM.

Kerb weight (kw) 

The weight of your tow vehicle, unloaded, with no passengers but with a full tank of petrol.

Kerb Weight - The weight of your tow vehicle, unloaded, with no passengers but with a full tank of petrol.
Gross vehicle mass (GVM)

This is the maximum permissible weight of your vehicle including all passengers, payload, accessories, roof racks, everything on your vehicle – including the tow ball weight. 

Gross Vehicle Mass (GVM)
Tow ball mass (TBM)

When hitched to your tow vehicle – the Tow ball mass in the percentage of weight exerted onto the vehicle’s tow ball from the camper. This can be up the 10% of the maximum towing specifications of the camper trailer. TBM will eat into your vehicle’s carrying capacity as this amount of weight must be deducted from your overall payload in the tow vehicle. (Including the weight of passengers etc.)

Tow ball mass (tbm)
Tare weight (tare) 

The tare weight is the weight of the camper trailer as delivered from the manufacturer, empty, and without any extra accessories, water in the tanks, gas bottles etc. This weight is listed on your compliance plate. 

Tare weight is the net weight of the trailer as delivered from the manufacturer
Aggregate trailer mass (ATM) 

The ATM is the maximum combined weight of the camper trailer, including a full payload, fluids, everything that is on the trailer, including the tow ball mass when it is NOT coupled to a vehicle. 

Aggregate trailer mass (atm)
Gross trailer mass (GTM) 

The GTM is the maximum combined weight of the camper trailer (and can be thought of as the ATM), including a full payload, fluids, everything that is on the trailer, including the tow ball mass when it is coupled to a vehicle. This weight is listed on the compliance plate. 

Gross trailer mass (gtm)
Combination mass (CM)

The Gross Combined Mass (GCM) is defined by the vehicle’s manufacturer and is the maximum limit of your combined rig (Tow vehicle and Camper Trailer) can weigh at any time. 

When you add your Gross Vehicle Mass (GVM) and your and your GTM (Gross Trailer Mass), the combined figure is your rig’s Combination Mass (CM) 

(GCM = GVM + GTM)

The CM of your complete setup must not exceed the GCM specified by the tow vehicle manufacturer. 

 

Gross Combination Mass explained

Putting it all together. What does it all mean?

Putting all this together can seem overwhelming, but it is easier than it looks. Basically, you need to do a couple of calculations during the buying process to figure out what camper trailer you can tow safely. The two most important equations you need to remeber are: 

GCM = GTM + GVM: This gives you the Maximum Combination Mass. The total weight of your tow vehicle, the trailer, and everything you intend to carry – including people. 

GCM – GVM = GTM: This gives you the maximum weight your vehicle can tow, The combined mass, minus the full weight of your tow vehicle which could end up being considerably less than the maximum specs dictate – so allow room for what you need to pack. G

An example: 2021 Subaru Outback 3.6R AWD

Let’s do an example together. Let’s look at the 2021 Subaru Outback 3.6R AWD – This has a Kerb weight (KW) of 1626kg, and a Gross vehicle mass (GVM) of 2,200kg, and a towing capacity of 1800kg. This leaves you with approximately 574kg of payload in your vehicle. 

If we pop on a camper like the Chariot – with a tow ball mass (TBM) of roughly 130kg that figure drops to 444kg. An average family of 3 (2 adults and one child) is roughly 170kg which drops you down to 274 kg that you can pack in the back. Now – This isn’t taking into consideration and aftermarket additions you have made to the vehicle – so make sure you add this as well. 

Upgrades can be made to some types of 4×4’s and Utes that can increase your GVM, however – this does not change the CM, so you may be able to put more in the tow vehicle – but you would need to reduce the size of the camper to compensate. 

The total Carrying capacity of the full setup, including your vehicle and trailer – the GCM (gross combination mass) = the GVM + GTM. So in this case, 2,200 + 1,800 = 4,000kg. 

A great option here would be the Chase or the Trooper’s as these campers both have a GTM of 1,500kg. In regards to the trailer – the larger the gap between the tare weight and the GTM as this is essentially your payload capacity. the bigger the gap – the more you can take. And this will leave you a bit of wriggle room, and more importantly you reduce your risk of running overweight, which is not only dangerous, but illegal. 

If unsure, take your vehicle to a weigh bridge to get yourself an updated and accurate Kerb weight that includes all fluids, petrol and any accessories you have added. Then pack it with your usual camping gear, chuck the kids in, and see how close you are getting to your GVM. With these updated specs – you will be able to check your shortlist and decide which is the best camper for your setup and vehicle. 

Questions?

Still have questions? Shoot us a message or give us a call and we would be more than happy to answer any questions you have regarding towing capacities  and Platinum Campers. 

Drive Safe & Happy Camping!