Weight Calculations

Weight Calculations

Towing a Caravan: Everything You Need to Know About Weights


Whether you’re new to towing a caravan or a seasoned pro, understanding the various weight ratings and calculations is crucial for safe and legal towing. This blog covers the key weights you need to pay attention to when pairing your tow vehicle and caravan.

Car Weight Ratings

When looking at tow vehicles, there are a few key weight figures to note:

– Tare Weight – The weight of the empty vehicle as it leaves the factory. Does not include passengers, fuel, or any accessories.

– Kerb Weight – The weight of the vehicle with a full tank of fuel and all standard equipment. Still does not include passengers or accessories.

– GVM (Gross Vehicle Mass) – The maximum allowable weight of the fully loaded vehicle, including all passengers, accessories, cargo, and tow ball weight.

– GCM (Gross Combined Mass) – The maximum allowable weight of the fully loaded vehicle plus a fully loaded trailer/caravan.


As a real world example, for a 2017 Isuzu MU-X:
Most of these weights can be found on www.carsales.com.au

– Tare Weight: 2,095kg
– Kerb Weight: 2,142kg
– GVM: 2,750kg
– GCM: 5,750kg


So for this vehicle, the GVM of 2,750kg is the fully loaded weight including passengers and the tow ball weight. The GCM is the combined maximum weight of the fully loaded vehicle and trailer.


Caravan Weight Ratings
For caravans, the key figures are:
These will be found on the compliance plate

– Tare Weight – The empty weight as it leaves the factory.

– ATM (Aggregate Trailer Mass) – The maximum allowable weight of the fully loaded caravan including all cargo, water, gas etc.

– Ball Weight – The downward force exerted on the tow vehicle’s tow ball by the fully loaded caravan.

– GTM (Gross Trailer Mass) – The total weight of the fully loaded caravan minus the ball weight. As the ball weight is carried by the vehicle, not the trailer wheels.


Using a specific caravan as an example:

– Tare Weight: 2,399kg
– ATM: 2,899kg
– Ball Weight: 193kg
– GTM: 2,706kg (ATM – Ball Weight)


Calculating Total Towing Mass

To determine if your vehicle can legally and safely tow your chosen caravan, you need to combine the weights of both.

Add together your vehicle’s real world loaded weight plus the caravan’s loaded weight. This total should be under your vehicle’s GCM rating.


As an example:

– Vehicle GCM: 5,750kg
– Vehicle Loaded Weight: 2,650kg (includes passengers and tow ball weight)
– Caravan Loaded Weight: 2,820kg
– Total Towing Mass: 5,470kg

In this example, the total mass is 5,470kg, which is under the GCM of 5,750kg, so it meets the legal and safe rating.

Use the Adelaide RV Weight Calculator – https://adelaiderv.com.au/weight-calculator/

For a handy online calculator to take the guesswork out of your weight calculations, visit the Adelaide RV website. Their weight calculator allows you to input your vehicle and caravan weights to determine compatibility. This provides peace of mind that your setup is within the ratings for safe and legal towing.


The most important takeaway when pairing a tow vehicle and caravan is to understand the various weight ratings and do your calculations. This will ensure both are within their limits for a safe towing experience. Check your owner’s manuals or compliance plates for the figures, and don’t overload. Happy and safe travels!