How do you calculate the towing capacity of a caravan?
In short, you determine how heavy a caravan you can safely tow by comparing the tow vehicle’s maximum allowed combined weight with the caravan’s own maximum laden mass, then choosing the lower figure and verifying tongue weight and hitch limits. This ensures both vehicle and trailer stay within their rated limits while keeping loads safe on the road.
Key figures you need to know
Before doing the math, collect the core ratings from the vehicle and caravan data plates or owner manuals. These figures spell out the practical limits you must respect when towing.
- GCWR (Gross Combined Weight Rating): the maximum allowed weight of the tow vehicle plus the trailer combined, as specified by the vehicle manufacturer.
- GVWR (Gross Vehicle Weight Rating) for the tow vehicle: the maximum weight of the tow vehicle itself with all payload (cargo, passengers, fuel, etc.).
- GVW (Gross Vehicle Weight) as actually loaded: the real weight of the tow vehicle with its current cargo and occupants.
- MTPLM (Maximum Technically Permissible Laden Mass) or ATM for the caravan: the maximum weight the caravan is allowed to be loaded to, including everything on board.
- Tongue weight (TW): the downward force the caravan places on the hitch, typically about 10–15% of the caravan’s loaded weight.
- Hitch rating: the maximum downward force the hitch or coupling system can safely transfer to the tow vehicle.
Concluding: These values determine the ceiling on what you can tow. The actual towing capacity will be the smallest of the vehicle’s trailer limit and the caravan’s own laden limit, with tongue weight and hitch limits also in play.
How to calculate the towing capacity (step by step)
Follow these steps to compute a safe, legal towing capacity and to verify it against the caravan you plan to tow.
- Identify the caravan’s MTPLM/ATM from its plate or the owner’s manual. This is the maximum loaded mass the caravan should carry.
- Find your tow vehicle’s GCWR and GVWR from its plate, manual, or manufacturer website.
- Estimate the loaded weight of the tow vehicle (GVW) when you’ll be traveling, including occupants, fuel, cargo, and any attachments.
- Calculate the maximum trailer weight allowed by the vehicle: Maximum trailer weight = GCWR − GVW.
- Compare that vehicle-based limit with the caravan’s MTPLM. The practical towing limit is the lower of the two values.
- Assess tongue weight: TW ≈ 10–15% of the caravan’s loaded weight. Ensure the hitch and vehicle can handle this load without exceeding ratings.
- Account for other constraints such as braking requirements, weight distribution, and local regulations, adjusting the load as needed.
Concluding: In practice, you’ll usually be safe towing a caravan if you stay within the smaller of the vehicle’s max trailer weight and the caravan’s MTPLM, while keeping tongue weight and hitch capacity within their limits.
Worked example
Consider a hypothetical setup to illustrate the calculation. The tow vehicle has a GCWR of 7,000 kg and a GVWR of 2,800 kg. The vehicle, loaded for a trip, has a GVW of 2,500 kg. The caravan has an MTPLM of 2,600 kg and is loaded to 2,300 kg. The hitch is rated for a maximum tongue weight of 350 kg.
- Max trailer weight from the vehicle side = GCWR − GVW = 7,000 − 2,500 = 4,500 kg.
- Caravan MTPLM (2,600 kg) is lower than the vehicle’s limit, so the caravan’s limit becomes the practical cap.
- Tongue weight at 12% of 2,600 kg ≈ 312 kg, which is below the hitch rating of 350 kg, so the hitch constraint is satisfied.
- Total mass for the combination would be 2,500 kg (vehicle) + 2,600 kg (caravan) = 5,100 kg, which is well below the GCWR of 7,000 kg, so overall mass is within limits.
Concluding: With these numbers, the caravan loaded to its MTPLM of 2,600 kg is within both vehicle and hitch limits, and the combination stays under the GCWR. If the caravan were heavier, or the vehicle more loaded, the limit would shift to the lower constraint.
Practical tips and safety notes
Towed loading must always comply with local laws and manufacturer guidance. Use a weight distribution hitch if appropriate, ensure legally required braking systems are in place for heavier caravans, and regularly weigh both the tow vehicle and caravan to verify actual loads match the calculated ones. When in doubt, consult the dealer or manufacturer for the exact ratings for your specific models.
Summary
The safe towing capacity of a caravan comes from the intersection of two major limits: the tow vehicle’s maximum trailing weight (derived from GCWR minus the vehicle’s actual weight) and the caravan’s own maximum laden mass (MTPLM/ATM). Tongue weight and hitch capacity must also fit within the system’s ratings. By gathering the relevant numbers, performing the simple subtraction and comparison, and verifying tongue weight and braking requirements, you can determine a safe, legal towing setup for your caravan.
What is the 85% rule for caravans?
You might have heard people with caravans refer to the '85% rule'. This is not a legal rule but a guide about how much you should safely tow if you're new to towing. It means that you're advised to only tow a caravan that weighs 85% or less of your car's kerb weight.
How do I calculate caravan towing weight?
The 85% rule states that novice caravanners should only tow caravans that weigh no more than 85% of the kerbweight of the tow car. As an example, if your tow car weighs 1600kg, a novice caravanner can safely and sensibly tow a tourer with an MTPLM weight of up to 1360kg. (1360 is 85% of 1600).
How do I work out what size caravan I can tow?
CALCULATION. Towing capacities are calculated by a number of maximum weight limits. The three most important numbers for you are Gross Vehicle Mass (GVM), Gross Trailer Mass (GTM), and Gross Combined Mass (GCM). In short, the GCM must be less than the sum of the GVM and the GTM combined.
What is the 80% rule for towing?
The 80% rule for towing is a safety guideline that recommends the weight of a fully loaded trailer should not exceed 80% of a vehicle's maximum towing capacity. This provides a safety margin for unpredictable conditions and reduces stress on the vehicle's engine, transmission, and brakes, helping to ensure better handling and a longer lifespan for components.
How it works
- Calculate your vehicle's limit: Find your vehicle's maximum towing capacity in the owner's manual or on the manufacturer's website.
- Calculate 80% of the limit: Multiply the maximum towing capacity by 0.800.800.80 to find your safe towing limit. For example, if your vehicle can tow 10,00010 comma 00010,000 pounds, your limit is 8,0008 comma 0008,000 pounds.
- Account for all weight: Ensure the total weight of the fully loaded trailer, including cargo and passengers in both the vehicle and the trailer, stays below this 80% limit.
Why it's important
- Safety margin: It provides a buffer for real-world factors like hills, curves, and sudden stops.
- Vehicle longevity: It reduces strain on key components like the engine, transmission, and brakes, which can extend their lifespan.
- Handling: Maintaining a margin helps ensure your vehicle can be steered and controlled effectively, even under load.
