Comprehensive Guide to Caravan Weighing
To help you understand your GoWeigh Caravan Weighing Report, we’ve consulted with leading independent motoring and towing experts. Here, we explain everything you need to know about your caravan weighing report.
This guide introduces key vehicle weights and explains how GoWeigh helps ensure you’re within limits. It’s important to differentiate between a vehicle’s limit (Gross Vehicle Mass – GVM) and its actual weight (Vehicle Weight), which should never exceed the GVM. While GoWeigh provides actual vehicle weights, you’ll need to find those for your specific vehicle and compare them to see if you were within limits.
GoWeigh Caravan Weighing Terms Explained
| Term for actual weight as per your GoWeigh report | Description | Term for Weight Maximum Limit | Where to find your limit |
|---|---|---|---|
| Unhitched Car Weight | How much your vehicle weighs. It is best to note in what state of load this is, for example unladen, or ready for a trip etc. | GVM – Gross Vehicle mass | Vehicle weight placard near the front door jamb, owner’s manual, car manufacturer’s website – be careful it is specific to your vehicle not general. |
| Front axle | The weight of the vehicle on the front axle. | Front axle limit | Owner’s manual, carmaker website – be careful it is specific to your vehicle not general |
| Rear axle | The weight of the vehicle on the rear axle. | Rear axle limit | Owner’s manual, carmaker website – be careful it is specific to your vehicle not general |
NOTE: All three weights differ when a trailer is hitched; the load (weight) on the rear axle increases, the load on the front axle decreases, and vehicle weight increases by the TBM (see below). This is why we ask you to do two weighs. However, the limits remain the same – therefore, your vehicle should be well under the limits above before it is hitched to the trailer.
Caravan & Trailer Towing Limits
| Term for actual weight as per your GoWeigh report | Description | Term for Weight Maximum Limit | Where to find your limit |
|---|---|---|---|
| Total Caravan Weight (1) | The maximum the towcar can tow, assuming the trailer has brakes. There is a lower limit for trailers without brakes but almost all caravans will exceed that limit so we won’t focus on it. | Braked Tow Capacity | Vehicle owner’s manual. |
| Total Caravan Weight (2) |
How much the trailer weighs. As with Unhitched Car Weight, make a note of what sort of load the trailer has; unladen, big trip, short trip etc. The weight of the caravan must be less than or equal to the Braked Tow Capacity AND then ATM, and you work off whichever is the lower figure as your maximum. |
ATM – Aggregate Trailer Mass | On the trailer’s placard on or near the drawbar. |
| Caravan Axle Weight | The weight on the trailer’s axles, so this excludes the towball mass. | GTM – Gross Trailer Mass | On the trailer’s placard on or near the drawbar. This is always less than the ATM. |
| Tow Ball Mass and % | The weight placed on the towball by the trailer in kg, and as a percentage of the trailer’s mass. Note that 10% TBM is often a maximum, and not something to aim for. The towcar maker will set a figure in kilograms and that is not to be exceeded. The percentage of TBM to trailer weight is not a formal limit, but the trailer maker may recommend a range. | Towball mass, or sometimes TBM, ball downforce. | The vehicle owner’s manual, OR towbar, or towbar tongue; whichever of the three is the least. The trailer maker may make a recommendation, but the actual maximum is set by the towcar’s limits. |
| Total Combination Weight | The maximum your vehicle AND trailer can weigh together. | GCM – Gross Combination Mass. | Owner’s manual, carmaker website – be careful it is specific to your vehicle not general. |
Calculating Your Vehicle & Towing Weights
Your report will also show a different set of weights for your vehicle; the weight on the front axle, rear axle and on the vehicle will have changed. This is due to the effect of the towball mass. You can use independent motoring journalist Robert Pepper’s Towing Weights Calculator to see the effects of different weights before you go to a GoWeigh weighbridge, and after you have your weights, then you can see the effect of changing them.