Caravan Weighing Example

Now, let’s run through a weighing example!

With the help of independent motoring journalist and towing expert Robert Pepper, he is an example of how to interpret your data.

• Vehicle GVM – example 3200kg
• Vehicle towball mass limit – 250kg
• Front axle limit – 1500kg
• Rear axle limit – 1850kg
• Trailer ATM – 2700kg
• Trailer GTM – 2600kg
• Vehicle GCM – 6000kg

Ideally, you should gather all that data before your weigh, but you can do it afterwards, and you don’t need all the data if you don’t need to check any specific limit.  Be careful to get the limits for your exact towcar and trailer, as the limits may change according to model year, engine type, transmission type and trim level, sometimes by 500kg or more. For example, not all Land Rover Defenders can tow 3500kg, and some Prados can tow 2500kg, others 3000kg.

So you’ve got your limits, then you go for your weigh. If you need help with that process watch this video.  With the weigh done, we can walk through an example report which will be sent via SMS or email to you immediately after your weigh.

This report shows that the caravan Total Caravan Weight is 2300kg, which must not exceed the ATM of 2700kg so we’re 400kg under there. The Braked Tow Capacity is 2500kg, so we’re 200kg under that limit.  The Unhitched Car Weight is 3000kg, and that must not exceed the GVM of 3200kg, so we’re 200kg under.  The Caravan to Car Ratio is 77%; this means the trailer is 77% of the towcar’s weight. You want your towcar heavier than the trailer for stability, so less than 100% is good although that alone does not guarantee stability. There is no regulation or limit for that ratio.

The Unhitched Car Weight of 3000kg is split 1400kg on the Front Axle Weight, which is 100kg under the front axle weight limit of 1500kg, and 1600kg on the Rear Axle Weight which is 250kg under the rear axle limit of 1850kg. The front/rear weight balance is 47/53% and is shown for those interested in vehicle dynamics; there’s no specific limit to worry about.

The Caravan Axle Weight (Total Caravan Weight minus Towball Mass) is 2060kg and shows how much weight is on the axles of the trailer; that must not exceed the GTM of 2600kg so we’re 540kg under.

Now we hitch the car to the trailer and that means we can calculate the Tow Ball Mass; it’s 240kg, which is close to our vehicle TBM limit of 250kg, noting the scales only report in 20kg increments. We also show the percentage of towball mass; in this case, it’s 10%.

We also have to add the Tow Ball Mass to the vehicle weight – so that’s now 3000kg of car plus 240kg of towball mass = 3240kg Hitched Car Weight and that’s unfortunately 40kg over the 3200kg GVM. We’ll fix that later.

The axle weights have changed too; the Front Axle Weight has gone from 1400kg to 1320kg (yes, that’s 80kg less) so still under the 1500kg limit.  The Rear Axle Weight has gone from 1600kg to 1920kg, another 320kg – despite the fact we only added 240kg TBM. The effect of the TBM is that we’ve added 320kg to the rear axle but lost 80kg from front axle, so the total corresponds to the 240kg Tow Ball Mass.

Finally, we can add the Total Caravan Weight to the Unhitched Car Weight to give us Total Combination Weight and that is 5300kg, which is 700kg under the GCM of 6000kg.

So we’ve exceeded two limits; the GVM by 40kg, and the rear axle load by 70kg.  What might we do?  Well, turns out there’s two e-bikes on the drawbar and a few tools in a front box. We can relocate them inside the caravan over the axles, which doesn’t change the caravan weight but it does reduce the towball mass. The generator is old and heavy, so that’s swapped out for a newer, much lighter version.

The fridge is carried in the van but in a similar position to the e-bikes, a long way forward of the van axles, so it adds to the TBM.  So the fridge gets relocated into the vehicle which also helps make the towcar heavier and the van lighter which contributes to stability. All these changes reduce the TBM from 240kg to 160kg, with a consequent reduction in hitched vehicle weight and rear axle load.

However, we’ve added 50kg of fridge to the car and we’re trying to get the weight down as it’s close to its GVM, so lucky there’s a few bags and tools we can relocate from the car to the centre of the van and that is enough to drop the vehicle weight. The van has plenty of payload (difference between its weight and ATM) so it can take the load, but remember it’s better to have weight in the towcar than the trailer.

With the changes made, back we go for another weigh, and this time it’s within limits even though we’ve only reduced total weight by 20kg!