Recently there have been rumours within the Facebook groups and Forums that I visit that brush on the possibility that there will be Weigh Stations set up by the Western Australian Police over this coming Easter, targeting Caravans. Whilst these rumours are without any substance, the subject still gets people anxious. Why? Because we all know that there is a little black plate affixed to our A- Frame near the tow hitch, that sets the maximum legal weights, but not many really understand what it all means.
Then there is a similar plate, usually in sticker form and generally adhered inside the driver’s side door frame, with a similar set of numbers.
Combined, they set the limits as to what your vehicle can tow, the maximum weight at the tow point and the maximum weight of what is actually being towed.
I don’t think for a moment that any Western Australian Police Officer really cares what weight each bit is, what they do want to know and quite rightly so, is, when you hit that Brake Pedal, that your Family is going to be able to come to a screaming stop, within a very short distance, without losing control, in one piece.
If you’re like me and are roaring down the road at 100kms/hr, with almost 6 tonne of steel behind the steering wheel, being blissfully ignorant of what these plates mean, could cost you more than just a Fine.
What is Tare Mass? (T)
Tare Mass, sometimes called the unladen weight. It is the weight of an empty vehicle or Caravan. By subtracting it from the Gross Weight (laden weight), the weight of all your kids’ toys, clothes, food and beer can be determined. It is the manufactured weight, from new, when originally registered. It is a Dry weight, so your water tanks and Gas Bottles were empty at the time it was weighed.
What is Aggregate Mass? (A)
The Aggregate Mass is an easy one – it is what your vehicle or caravan weighs, with everything in and on it, as it stands, unhitched.
What is Gross Mass (G)
This is the maximum weight of the loaded caravan that can be supported by its wheels, not counting the portion supported by the car when hitched. This rating is set by the manufacturer and cannot be exceeded.
What is Axle-Group Rating?
This is the maximum safe working load the axles have been designed to with-stand under the highest shock loading's that they are likely to be subjected to.
What is Ball Loading at Tare Mass?
This is the weight at the hitch of your Caravan as supplied from new, when originally registered. It is a Dry weight, so your water tanks and Gas Bottles were empty at the time.
What is Maximum Permissible Ball Loading?
This is the maximum safe working load that your Tow Hitch has been designed to be subjected to.
How to Calculate.
To calculate our combined weight, so as to find out if we fall beneath our maximum legal Towing Capacity we are going to need the information above, from both the Vehicle and the Caravan.
Unless you have a set of vehicle scales sitting in the shed, you will have to load up your Vehicle, with all the normal passengers and equipment, hook up your Tow, fully loaded as well and head to a public weigh station.
You will first need to weigh your Vehicle, with all those accessories you fitted, and then you’re Caravan. This gives you the Aggregate Mass of both.
If you’re rolling your eyes at the prospect of the inconvenience of having to do this, remember, if it’s a Police Officer doing the weighing and your over, you get to unhitch your Caravan and have not only a fine, but towage fees to pay as well.
Lastly, you will need a set of Tow Ball Scales to get the Ball Weight of your Caravan. I purchased a set, as knowing the weight of the ball helps me distribute the load in my Caravan evenly, each time I pack.
I Googled my Vehicle Manufacturers specification sheet and came up with its weights and towing information.
Vehicle Tare and Gross Mass
Gross Vehicle Mass Weight Reductions
Vehicle Rated Towing Capacities
The Caravan information is on the little black plate affixed to our A- Frame, the VIN Plate.
I now have all the information I need to calculate.
Vehicle
Gross Mass of 2880 kgs
Minus
Weighed Aggregate Mass of 2415 kgs
Equals
Weight Remaining of 456 kgs
Caravan
Gross Mass of 2995 kgs
Minus
Weighed Aggregate Mass of 2990 kgs
Equals
Weight Remaining of 5 kgs
From the Vehicle Manufacturers specification sheet, my maximum Towing Capacity is 3000 Kgs, as the Caravan weighs in at 2990 kgs, it is a legal weight.
From Caravan Manufacturers VIN Plate, my maximum Towing Capacity is 2995 Kgs, as the Caravan weighs in at 2990 kgs, it is a legal weight.
My factory fitted Tow Bar is rated at 300 kgs.
My Ball Weight was 275 kgs, so this is a legal weight.
From the Vehicle Manufacturers specification sheet, if I add 275 kgs of Ball Weight I must deduct 310 kgs off the Vehicle Weight Remaining of 456 kgs. This gives me 146 kgs of Luggage I could add to the Vehicle and still be a legal weight.
(The 310 kgs was found by subtracting the reduced loaded vehicle mass of 270 kgs from 350 kgs, and then dividing it by two, which is 40 kgs added to 270 Kgs gives me a Reduced loaded vehicle mass of 310 kgs for a Ball Weight of 275 kgs.)
The Weighed Aggregate Mass of both the Vehicle and Caravan were taken with full fuel, water and gas cylinders.
I now know that I am not only road legal and my Caravan Insurance is valid, but when my foot hits the brakes and my Families lives are on the line, I can pull almost 6 tonne of screaming steel up.
That in the end is what really matters.
A Timely Reminder.
The following photos were taken by Clayton's Towing last week. No one was seriously hurt.
There is a message in them for all of us.
Check the tightness of your Tow Ball, Make sure your Chains are attached to the Vehicle securely, not the Tow Bar and maintain your Hitch.
If you need your Brakes checked and adjusted, give Westcoast Trailer and Caravan Services a call, they come to you!