I recently had the pleasure of a caravan weighing session for a proud new owner of a GWM Tank 300 Diesel. It was interesting to learn a little more about this relatively new caravan hauler.
Was it capable of towing a caravan and payload with reasonable safety margins?
My customer was new to caravanning and insisted on just one luxury – air conditioning … and that means being able to take a generator as an essential part of the camping trip. This was a sensible caravan and tow vehicle matchup. The GWM Tank 300 has a maximum braked towing capacity of 3,000kg and the chosen caravan, a single axle Century Caravan, has an ATM of just 2,400kg. That’s a safe and great van to tow vehicle weight ratio of 80%. (The van weighs 80% of the tow vehicle.)
Up on the scales, the rig had accessories, water tanks, extra refrigeration, and the crucial generator for off-grid camping trips. Fuel is full with driver and one passenger on board, with the exception of the travelling cat.
How did it weigh in?
The final configuration required some balance shifting. The generator was placed in the rear luggage area of the Tank, and the scales recorded the following:
The caravan was almost maxed-out at 2,364kg, giving a reasonable, 222kg on the towball of the SUV.
With the 35kg generator sitting over the back axle of the GWM Tank 300 4WD diesel – the 2,880kg GVM of the tow vehicle was well under the limit, at 2,751kg, making a generous 129kg margin but watch out for that rear axle limit!
The rear axle was also in check with a fairly fine margin of 45kg before it’s overloaded. The overall GCM or gross combined mass, that’s the limit of the entire towing rig together, came well inside limits with a whopping 710kg margin. Great! That means there’s plenty of braking capacity!
Congratulations to this proud couple of new travellers for taking the time to configure their caravan and tow vehicle for safe family trips.
Let’s explain what these figures mean and how to interpret them …
How much more can be placed in the caravan? Looking at the smallest margin in the chart, 36kg is available for the ATM of the caravan. If you added 37kg anywhere in the caravan, it would be overweight. You could put 36kg of fresh water perhaps in a container and locate that container in a position either over or just in front of the caravan’s axles.
What if you put that 36kg in the front boot of the caravan or the tool box on the draw bar? If you added the 36kg in these locations, there is a chance that it could overload the rear axle of the towing vehicle. It may be okay, but it would be best to load the weight just in front of the caravan’s axles where no weight would transfer to the tow ball and then the rear axle of the car.
How much extra can be place in the car?
At a quick glance, the rear axle load has only 45kg margin. That means that if you add a 12 volt fridge to the back of the car, over the rear axle, and if that fridge and contents weighed 45kgs, then the axle would be at maximum capacity. If you move this same weight to the floor, in front of the back seat, then the weight would be spread between the tow vehicle’s front and rear axles and your could add just a little more weight, or keep the margin for safety.
The next limitation is the GVM, with 129kg margin available. The problem is you cannot add this 129kg to anywhere in the car because it would overload the rear axle capacity of the car. The only amount of extra weight available, in this case, is 36kg on or before the axles of the caravan, and another 45kg as far forward in the car as possible. Ideally, on the floor, and behind the front seats.
These margins might seem close to many of us who do not have the luxury of weighing a caravan before every trip. This is why I recommend the app from LoadMate.
With LoadMate, you measure locations of various items one time. For example, tools in the front boot, passengers in the tow car’s rear seats, the dog in the rear compartment, and an extra 20kgs of food in the food storage under the seats of the caravan.
As you load each group of items into those locations, the app automatically presents all the weights and compares the recordings to the ATM, the GVM, and the GCM. There is also load balance calculated for you – so you know that your caravan and towing vehicle’s weight and balance is correct before you go, and you can easily review these weights before every road trip with LoadMate and a set of bathroom scales!
I can assist with setting up LoadMate in your caravan. Just request the extra time allowance when you book your mobile caravan weigh station appointment. I can advise on costs. The only requirement is for you to first measure your caravan and car weights empty, and before loading.
Call today at 0474 911 123 to discuss setting up the LoadMate app today!
Glossary:
ATM (Aggregate trailer mass – caravan)
The total maximum weight allowed of the entire caravan, including clothes, food, contents and water tanks.
Rear axle capacity (Tow vehicle)
The maximum allowed weight on the back wheels of the tow vehicle. This measure is critical for a tow vehicle when a caravan is hitched to the towball. The tow ball is around one metre or more behind the rear axle and the leverage effect multiplies the tow ball downforce on the back axle of the tow vehicle.
TBM (Tow ball mass)
The maximum weight allowed for the tow ball when the caravan is attached to the tow vehicle.
GVM (Gross vehicle mass – tow vehicle)
This is the maximum weight allowed for just the tow vehicle. The tow vehicle also carries the weight of the towball when a caravan is hitched on, and this weight must include anything inside the vehicle, passengers, fuel, and cargo.
GCM (Gross combined mass – both vehicles)
This is the weight of both vehicles, the caravan and the tow vehicle, when they are combined or hitched. This GCM is a limit and cannot be exceeded.
Leave a Reply