Caravan Towing Weights Explained
Understanding caravan towing weights is crucial for safe and legal towing, ensuring you stay within your vehicle's capabilities, and avoiding potential warranty and insurance issues. It can be complicated, as there are lots of terms to familiarise yourself with, but hopefully, our guide will make things easier. We'll break down the key terms and regulations surrounding towing limits and give you some examples to help you calculate them yourself. You'll be a pro before you know it!
Why are caravan weights important?
Properly managing the weight of your caravan, tow vehicle, and their combined load is crucial for several reasons:
- Safety: Overloading can impact handling, braking, and stability. This can cause your caravan to sway, making towing dangerous, and increasing the risk of accidents.
- Damage: Incorrect weight distribution or exceeding weight limits can put excessive strain on your caravan, including its suspension, leading to premature wear, damaged components, and reduced stability.
- Legal compliance: Exceeding the Gross Vehicle Mass (GVM) or Aggregate Trailer Mass (ATM) can result in fines and legal issues, putting your safety and others at risk.
- Warranty: Overloading your vehicle may void its warranty, leaving you unprotected against potential repairs.
- Insurance: Exceeding weight limits can invalidate your insurance, leading to denied claims if an accident occurs, as insurers may argue that the overload contributed to the damage.
Key terms: Caravan weights explained
Essentially, the Tare Weight indicates how much load can be safely added to your caravan, while the Aggregate Trailer Mass (ATM) limits the total weight to prevent overloading. The Gross Vehicle Mass (GVM) ensures your towing vehicle can handle the combined weight, maintaining safe towing conditions. Understanding each of these roles is crucial for safe and legal towing.
Tare weight of a caravan
The Tare Weight of a caravan refers to its weight when empty, excluding personal items, water, gas bottles, and passengers. However, it includes essential fluids like oil, 10 litres of fuel, and any factory-installed equipment. Accessories such as tow bars, bull bars, or roof racks are not part of the Tare Weight.
Why it's important: The Tare Weight is crucial for understanding how much weight your caravan contributes to the total towing setup. It is the base weight from which the maximum allowable weight (ATM for caravans and GVM for tow vehicles) is calculated. Knowing your caravan's Tare Weight helps you choose a safe and compliant towing vehicle.
Where to find it: The Tare Weight is on the caravan's compliance plate, which is usually located on the side of the vehicle.
Caravan Kerb Weight vs Tare Weight
You might also come across the term Kerb Weight (KW), which is similar to Tare Weight but includes a full tank of fuel.
Caravan Aggregate Trailer Mass (ATM)
The Aggregate Trailer Mass (ATM) refers to the maximum allowable weight of your caravan when it is fully loaded and unhitched from your tow vehicle. This weight includes the caravan itself, any modifications, and all your packing essentials, such as water in the tanks, gas bottles, luggage, food, clothes, and more. Caravan manufacturers set the ATM at the time of production.
Why it's important: Exceeding the ATM can lead to dangerous towing conditions, including instability and poor handling. It may also be illegal, as it could violate government or local towing regulations. It can also void your insurance, leaving you unprotected if you have an accident.
Where to find it: The maximum permissible ATM is listed on your caravan's compliance plate, typically found on the side of the caravan.
How to determine caravan weight: If you're unsure about your caravan's fully loaded weight, visit a public weighbridge to get an accurate reading. This will help you determine how much additional weight you can safely add. You can also use apps like LoadMate to track your caravan's weight.
Caravan GVM (Gross Vehicle Mass)
The Gross Vehicle Mass (GVM) refers to the maximum weight your tow vehicle is designed to carry, as specified by the manufacturer. This includes the vehicle's weight, passengers, luggage, gear, fuel, and the tow ball mass from the caravan (also known as the Tow Ball Mass or TBM—more on that below). Essentially, the GVM is the total weight your towing vehicle can safely handle, including the weight of the caravan attached.
Why it's important: Exceeding the GVM can seriously affect your tow vehicle's performance, including braking, handling, and acceleration. This can create safety hazards such as loss of control or even mechanical failure. Going over the GVM may also result in fines, insurance issues, and potentially void your vehicle's warranty.
Where to find it: The GVM is set by the vehicle manufacturer and can typically be found on the vehicle's compliance plate or in the owner's manual.
Caravan tow ball weight
Also referred to as Tow Ball Mass (TBM) or Maximum Tow Ball Weight, this is the maximum weight that can be transferred from your caravan's coupling to your vehicle's tow ball. It represents the downward force exerted on your tow vehicle when the caravan is hitched up.
Why it's important: The tow ball mass places a load on your tow vehicle's rear, and your vehicle is only designed to handle a certain amount of weight. Exceeding this limit can lead to handling issues, such as poor control or increased wear on your towing vehicle.
Where to find it: The empty tow ball weight is usually listed on your caravan's compliance plate. The actual tow ball load can vary depending on how your caravan is loaded, including luggage weight, water tanks, and gas bottles. The easiest way to measure this is with a tow ball weight scale.
Gross Trailer Mass (GTM)
Gross Trailer Mass (GTM) refers to the maximum weight on the caravan's axles when it is hitched to a tow vehicle. Unlike the Aggregate Trailer Mass (ATM), the GTM excludes the tow ball weight, which is transferred to the car and not supported by the caravan's jockey wheel when connected to a vehicle.
Where to find it: The GTM is typically listed on your caravan's compliance plate, which is usually found on the side of the caravan. You can also calculate it by subtracting the tow ball weight from your caravan's ATM.
Gross Combined Mass (GCM)
Gross Combination Mass (GCM) is the maximum allowable weight of your car and caravan combined, as set by the vehicle manufacturer. This includes everything—passengers, luggage, gear, fuel, water, and any accessories loaded into both your car and caravan. Essentially, it's the total weight of your entire towing setup.
Where to find it: Your vehicle's Gross Combined Mass and towing capacity are in the owner's manual or on the manufacturer's website.
Car payload
To calculate your car's payload (the maximum weight you can load into your tow vehicle), subtract its kerb weight from its Gross Vehicle Mass (GVM). The difference between these figures gives you the maximum weight your vehicle can carry, assuming a full fuel tank.
Caravan payload
To determine your caravan's payload (how much weight you can load), subtract the Tare weight from the Aggregate Trailer Mass (ATM). Remember that any modifications made after the caravan's build, accessories, luggage, gas bottles, and tank water are accounted for in the Tare weight and must be subtracted from your available payload.
How to safely tow your caravan
To tow your caravan safely, it's crucial to understand key terms like Tare, ATM, GVM, and TBM. These terms help ensure you stay within legal weight limits and maintain safety on the road. Don't exceed the recommended Gross Combined Mass (GCM)—it's essential for safety and compliance.
Additional tips for safe towing include ensuring your caravan is loaded correctly and the weight evenly distributed to avoid instability. Double-check that the tow ball is securely attached, the caravan's brakes and lights are functioning, and the safety chains are correctly connected.
It's also essential to regularly inspect tyre pressures on both your towing vehicle and caravan. Drive cautiously by allowing extra braking distance, avoiding sharp turns, and not making sudden lane changes. Always adhere to legal speed limits, and practice reversing with your caravan, as it behaves differently from a solo vehicle. Ensure your mirrors are correctly adjusted, and the caravan is well-balanced for optimal control. Safe towing starts with preparation and awareness!
Some examples that might help!
Now that you know the essential weights to note and what they mean, here are a couple of examples of how to calculate various weights and what vehicle will suit what type of caravan.
Example 1:
Start by creating a list of your vehicle weights. For example,
- Kerb weight: 2330kg
- Gross vehicle mass: 2900kg
- Maximum payload: 570kg
- Maximum ball weight: 250kg
- Maximum towing capacity: 2500kg
- Gross combination mass: 5290kg
In this instance, towing a caravan at your maximum towing capacity of 2500kg leaves you with 2790kg of your gross combination mass (GCM). If your caravan's ball weight is at the maximum of 250kg, that leaves 320kg of your GVM or maximum payload for everybody in your car, luggage, etc. A tow vehicle of this size can generally tow a small caravan.
Example 2:
- Kerb weight: 2230kg
- Gross vehicle mass: 2990kg
- Maximum payload: 760kg
- Maximum ball weight: 300kg
- Maximum towing capacity: 3000kg
- Gross combination mass: 5990kg
Towing a caravan at your maximum towing capacity of 3000kg leaves you with 2990kg of your gross combination mass (GCM). If your caravan's ball weight is at the maximum of 250kg, that leaves 320kg of your GVM or maximum payload for everybody in your car, luggage, etc. A tow vehicle of this size can generally tow a family caravan.