Kerb weight, also known as curb weight, refers to the total weight of a vehicle when it is unoccupied and ready for use, including all fluids, fuel and standard equipment but without any passengers or cargo.

Is curb weight the same as gross vehicle weight?

No, curb weight is the weight of the vehicle without passengers or cargo, while gross vehicle weight includes the curb weight plus the weight of passengers, cargo, and any additional equipment.

How does curb weight affect towing capacity?

Curb weight is used to determine the vehicle's payload and towing capacity. Understanding the curb weight helps ensure that you do not exceed the maximum weight limits, which can impact vehicle performance and safety.

This is the weight of an empty standard vehicle with all of its fluids (for example, oils and coolants) and specifically 10 litres of fuel in the tank. Essentially, it is the same as the Kerb Weight or Mass but with only 10 litres of fuel instead of a full tank.

Does tare weight include the weight of aftermarket accessories?

No, tare weight typically does not include the weight of aftermarket accessories. These should be added to the tare weight to determine the actual loaded weight of the vehicle.

Payload refers to the maximum weight a vehicle can carry, including passengers and cargo. It specifically denotes the weight capacity available for additional items beyond the vehicle's own weight, such as luggage, equipment, or other goods. Payload is crucial especially for those who frequently carry heavy loads or tow trailers, as exceeding the payload capacity can lead to safety issues and vehicle damage.

How does towball download affect my vehicle's allowable payload?

The towball download is the downward force the trailer exerts on the hitch and is considered part of your vehicle's allowable payload. For example, if your vehicle has a payload capacity of 800 kg and the towball download is 100 kg, you have 700 kg left for passengers, cargo, and other equipment. It's essential to factor in the towball download to ensure you stay within limits.

What is GVM (Gross Vehicle Mass)?

Gross Vehicle Mass (GVM), also known as Gross Vehicle Weight (GVW), refers to the total maximum weight of a vehicle when fully loaded, including the vehicle's own weight, passengers, cargo, and any additional accessories or equipment. Essentially, it represents the maximum weight the vehicle can safely carry without exceeding its structural limits or compromising safety.

How can I ensure I'm within the GVM limits?

Use a towing calculator to factor in all weights, including passengers, cargo, and any modifications, to ensure the total does not exceed the GVM. Regularly check your load distribution and weight.

What does it mean to get a GVM upgrade?

A GVM upgrade involves modifying your vehicle to increase its Gross Vehicle Mass (GVM) beyond the manufacturer's original specifications. This typically includes upgrading suspension components, brakes, and other parts to handle the increased weight safely. GVM upgrades are often done for vehicles used in heavy-duty applications or when additional payload capacity is required. It's important to ensure that the upgrade is done by a certified professional and that the vehicle remains compliant with legal and safety standards.

Can a GVM upgrade increase my tow capacity?

No, a GVM upgrade does not directly increase your vehicle's tow capacity. It increases the allowable weight your vehicle can carry, but the towing capacity is primarily determined by the vehicle's engine, transmission, brakes, and other factors specified by the manufacturer. While a GVM upgrade can help manage higher payloads, you must still adhere to the original tow capacity limits set by the vehicle manufacturer.

Does a GVM upgrade increase GCM?

Not automatically. A GVM upgrade raises the legal loaded weight of the tow vehicle only. GCM is a separate manufacturer limit covering the combined weight of vehicle and trailer, and it only increases if the supplier also holds a matching GCM upgrade certification for your specific make and model. Without that, towing a heavy van after a GVM upgrade can still leave you over GCM.

What is GCM (Gross Combined Mass)?

Gross Combined Mass (GCM) refers to the maximum allowable weight of a combination of vehicles, typically a towing vehicle (such as a truck or SUV) and its trailer, when fully loaded. It represents the combined total weight of both the towing vehicle and the trailer, including all passengers, cargo, fluids, and any additional equipment.

How do I find my vehicle's GCM?

You can find the GCM in your vehicle's owner manual, on the manufacturer's website, or on the compliance plate typically located in the engine bay or door sill.

Do I need to add towball download to calculate GCM?

No, you do not need to add the towball download separately when calculating GCM if the total tow weight already includes it. The GCM should already account for the combined weight of the vehicle, its load, and the trailer, including the towball download.

How can I ensure I'm within the GCM limits?

Use a towing calculator to factor in all weights, including passengers, cargo, and trailer load, and ensure the total does not exceed the GCM.

What does GCM stand for and what does it mean?

GCM stands for Gross Combination Mass (sometimes called Gross Combined Mass). It's the maximum allowed weight of your tow vehicle and a fully loaded trailer added together. It's set by the vehicle manufacturer and is usually different from – and lower than – simply adding GVM and towing capacity.

What is GCM of a vehicle in simple terms?

Think of GCM as the heaviest legal weight you and your caravan can hit the scales at while still hitched together. If your 4WD has a 6,000 kg GCM, the loaded vehicle plus the loaded caravan must come in at or under 6,000 kg combined – no matter what the individual GVM and tow rating allow.

Can GCM be increased on a vehicle?

Yes, for some popular Australian tow vehicles. Second-stage manufacturer (SSM) GCM upgrades are available for models like the Ford Ranger, Toyota LandCruiser 79/300, Isuzu D-Max/MU-X and Nissan Patrol Y62 through engineers like Lovells, Pedders and ARB. They require ICV/engineering certification and aren't offered for every vehicle. See our GVM & GCM upgrades guide for the current list.

What is Tow Capacity Braked?

Tow Capacity Braked refers to the maximum weight a vehicle can tow when the trailer being towed is equipped with its own braking system. This specification indicates the maximum load the towing vehicle can handle while the trailer's brakes assist in slowing down and stopping the combined vehicle-trailer unit safely. For most vehicles, this is any towing weight above 750kg.

What is the difference between braked and unbraked towing capacity?

Braked towing capacity refers to the maximum weight your vehicle can tow when the trailer has its own braking system, while unbraked towing capacity refers to the maximum weight your vehicle can tow when the trailer does not have its own brakes.

Does the towball download affect braked towing capacity?

Yes, the towball download is a factor in your vehicle's overall towing capacity. It should be included in your calculations to ensure you do not exceed the maximum allowable weight.

Can I increase my vehicle's braked towing capacity?

Increasing braked towing capacity is generally not recommended, as it is determined by the manufacturer based on the vehicle's design and capabilities. Always adhere to the manufacturer's specifications to maintain safety and compliance.

What is Tare Weight (Non-Vehicle)?

Tare weight refers to the weight of the trailer when it is empty and does not contain any cargo, passengers, or additional items. It includes the weight of the vehicle's structure, chassis, wheels, and any installed equipment or features (such as gas bottles for caravans), but does not include the weight of any cargo, water, fuel, or other items that may be carried when the vehicle is in use.

How do I find the tare weight of my trailer or caravan?

The tare weight can usually be found on the compliance plate attached to the trailer or caravan, in the owner's manual, or provided by the manufacturer.

Does the tare weight include water and gas tanks?

Typically, tare weight includes empty water and gas tanks. The weight of any filled tanks should be added to the tare weight to calculate the total loaded weight.

Can the tare weight change over time?

Yes, any modifications, added accessories, or wear and tear will change the tare weight. It's important to recheck the weight if significant changes are made to the trailer or caravan.

What is Towball Download?

Towball download, also known as tongue weight or hitch weight, refers to the downward force exerted on the tow vehicle's towball or hitch by the tongue of a trailer or caravan when it is connected for towing. It is the weight that presses down on the rear of the towing vehicle and is essential for maintaining stability and control while towing.

How do I measure towball download?

Towball download can be measured using a towball scale. Place the scale under the trailer's hitch and read the weight directly from the scale.

What should my towball download be?

Typically, the towball download should be around 10% of the trailer's total weight. Refer to your vehicle and trailer's manufacturer specifications for exact recommendations.

Can I adjust the towball download?

Yes, you can adjust the towball download by redistributing the weight within the trailer. Moving heavier items towards or away from the hitch can increase or decrease the towball download.

What is Aggregate Trailer Mass (ATM)?

Aggregate Trailer Mass (ATM) refers to the maximum loaded weight of a trailer unhitched, including its own weight and the weight of any cargo, passengers, and fluids it may carry. Essentially, ATM represents the total mass that the trailer can safely support when fully loaded. This includes the weight of the trailer's structure, chassis, wheels, and any installed equipment or features, as well as the weight of any items being transported.

How is ATM different from Gross Trailer Mass (GTM)?

ATM includes the total weight of the trailer and its load, while GTM is the portion of the ATM that is supported by the trailer's axles, not including the towball download.

How do I find my trailer's ATM?

The ATM is usually specified on the trailer's compliance plate, in the owner's manual, or provided by the manufacturer.

How do I ensure I'm within the ATM limit?

Weigh your trailer when fully loaded, including all cargo and accessories, to ensure the total weight does not exceed the specified ATM.

What is Gross Trailer Mass (GTM)?

Gross Trailer Mass (GTM) refers to the total weight of a trailer hitched to your vehicle when it is fully loaded, including its own weight as well as the weight of any cargo, passengers, and fluids it may carry. Essentially, GTM represents the maximum mass that the trailer is designed to support when in use.

How can I find my trailer's GTM?

The GTM can be found on the trailer's compliance plate, in the owner's manual, or provided by the manufacturer.

Why is GTM important?

GTM is essential for ensuring that the trailer's axles and wheels are not overloaded, which can lead to tire failure, axle damage, and unsafe towing conditions.

How does GTM differ from Aggregate Trailer Mass (ATM)?

GTM is the weight supported by the trailer's axles, while ATM includes the entire weight of the trailer and its load, including the portion supported by the towing vehicle's towball.

What is Rear Max Axle Load (RMAL)?

Rear Max Axle Load, often abbreviated as RMAL, refers to the maximum weight that can be supported by the rear axle of a vehicle. It represents the maximum load that the rear axle, along with its associated components such as tires, suspension, and brakes, can safely carry without exceeding their design limits.

Can rear max axle load be increased?

Increasing the rear max axle load typically requires modifications to the suspension and axles and must be done in compliance with legal and safety standards. Consult with a professional before making any changes.

How do I ensure I'm within the rear max axle load limit?

To ensure you are within the rear max axle load limit, weigh your vehicle when fully loaded and ensure the rear axle load does not exceed the specified limit.

Does the rear max axle load include the weight of the trailer?

The rear max axle load includes the weight transferred to the vehicle's rear axle by the trailer through the towball download. Ensure the combined load does not exceed the axle limit.

How does loading a tow weight increase the weight on the rear axle?

Loading a tow weight can significantly increase the weight on the rear axle, often by around 150%. This happens because the towball download from the trailer adds additional force directly onto the vehicle's rear axle. It's essential to consider this increased load to avoid exceeding the rear max axle load limit, ensuring safe towing and vehicle stability.

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Understand Towing | Learn How to Tow Safely in Australia

GVM, GCM, ATM, GTM, payload, kerb weight and tare — every Australian towing weight term explained in plain English, with worked examples, common mistakes and step-by-step guidance so you can tow safely, legally and confidently anywhere in Australia.