TOW VEHICLE & CARAVAN WEIGHTS.

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IS YOUR CARAVAN AND TOW VEHICLE OVERWEIGHT, DANGEROUS AND NOT LEGALLY ALLOWED ON THE ROAD?

  Truck Friendly’s Ken Wilson advises that it is estimated that between 60 and 80% of all caravan and tow vehicle set ups on the road today are overweight in some respect. An TMR safety officer advised that a recent caravan safety check on the Fraser Coast recorded approx. 80% of caravans tested were overweight. It has been known as a problem within the industry for some time.

This is a staggering statistic and one now attracting more and more attention from authorities.


As driver it is your responsibility to ensure that the vehicle you are driving and any trailer/caravan that you are towing is within the weight limits as specified by the vehicle manufacturer. Apart from being very dangerous, heavy fines can result. A recent court case in Victoria saw a driver charged relating to having an overloaded vehicle towing a caravan involved in a double fatality.


The manufacturers of your caravan and your tow vehicle have set strict weight limits that should not be exceeded. To do so puts you and other road users at serious risk.


We will look at both tow vehicle and caravan in separate articles on the Truck Friendly Facebook page over the next couple of days. The articles are also available on the Truck Friendly Facebook page.

https://www.facebook.com/truckfriendly.com.au

PART 1 – THE TOW VEHICLE - (Can also include the Motorhomes)

  

So how do we calculate legal weights, and not rely on the “I’ve been towing caravans for all my life. I haven’t had a problem, - Yet” syndrome. 


You will hear every excuse under the sun, but facts are facts whether we like them or not. Be informed and make your own choices from there. I am not judging, only helping educate. What you do with the information is your responsibility and must live with the consequences, I have done mine.


By checking your vehicles compliance plate and owner’s manual you will find the manufactures specifications that you will need to comply with, if you are legally allowed on the road.


Firstly, let’s look at the tow vehicle’s manual and compliance plate, for the following weights.

Let’s start with the basics.


GVM (Gross Vehicle Mass) This is the maximum operating weight of the vehicle. This will include all fluids, fuel, driver, passengers, bull bar, towbar, accessories, all cargo, including that boat on the roof etc. AND the tow ball download weight from your caravan. In short, the total allowed weight on the vehicles wheels when it is on the road.


TARE or KERB WEIGHT This is the weight of your basic vehicle as it came out of the factory with 10 litres of fuel.


If you subtract the Tare or Kerb weight from the GVM that will give you the maximum permissible load that this vehicle can legally carry. 


For example: - Lets do a quick internet search of a popular tow vehicle we can all relate to, a Landcruiser GLX turbo diesel. All weights are approximate and will vary depending on personal choices and the Landcruiser chosen at random.


https://www.toyota.com.au/landcruiser-200/range


This table shows that the Landcruiser 200 GLX turbo diesel has a GVM of 3,350 kg less the Kerb weight of 2,740 kg will mean that vehicle can legally carry a load of 610 kg. (3,350 – 2,740 = 610)


Now, here is where it gets personal. What do you and your partner and any passengers weigh? Let’s say we are all fit and healthy and the combined weight of mum and dad is 170kg. 


No discussion on who makes up the larger part of the randomly chosen weight please. 


So, 610 kg load available less 170 kg leaves 440 kg for cargo. Or does it? No.

Don’t forget this vehicle has a 138-litre fuel tank and the Kerb weight usually only includes 10 litres of fuel so that is another 128kg of fuel. (440 kg less 128 kg leaves 312 kg for cargo and aftermarket accessories)


Now with 312 kg of load weight let’s allow for the metal bull bar at 80 kg, a camping fridge with a slab of beer in it at approx. 50 kg. Our 312 kg of cargo is now 312 – 80 – 50 = 182 kg of cargo allowed.


We still haven’t packed any camping gear, cloths, food, recovery gear, spare fuel or water. We haven’t allowed for that winch in the 80 kg bull bar nor the side steps, roof racks, long range fuel tanks and any other accessories or items.


Put 2 other people as passengers at 170 kg? in the car and you will be almost right on the maximum limit of weight you can carry in the vehicle.


Have I missed anything? Maybe we would like to put a tinnie on the roof and outboard motor in the back at another 150 kg. Suddenly we are overweight.

The sad thing is we have left the caravan behind. 


The Landcruiser is a popular tow vehicle and rightly so. They are great when used properly and boast a 3,500 kg towing capacity and 350 kg tow ball load. In the above example with a large caravan in tow we have a vehicle which is now approx. ½ tonne overweight and very illegal and dangerous to drive.


I have not done this example to scare anyone, only to help educate on what to look for when buying and loading a vehicle especially when using it to tow a large caravan. All vehicles are different, and all owners are different. Some carry 3 kitchen sinks and others carry a plastic wash up bucket instead.


Weigh the stuff in your vehicle to see what you can do without.

PART 2 – THE CARAVAN WEIGHTS – A simple explanation.

  Ken Wilson from the Truck Friendly road safety program advises that our caravans have been designed by industry experts to be a home away from home and a safe trailer to tow.

 

They should be safe to tow without any added extra, so called safety equipment if the manufactures instructions and recommendations are followed and the correctly matched tow vehicle used. 


After market ‘safety’ features should only be used as an extra safety option, if needed, if recommended by a qualified person for your individual situation and should not be relied on to compensate for bad loading and towing practices. 


Do the basics right and the caravan should tow well. With that in mind caravans come with certain limits on what we can carry in them. 


Caravans are not designed as a load carrying trailer like a car trailer or box trailer. It is designed to take the basic necessities and provide a comfortable living environment for the owners while travelling. They have a limited load carrying capacity so that they can keep down the weight. The lighter a caravan the more vehicles that can legally tow it, the better the fuel consumption for the tow vehicle and therefore the more sales the caravan manufacturer will make. It’s basic commercial strategy. Nothing wrong with that.


It stands to reason that they can therefore be easily overloaded, especially if the owner wants to take too much gear with them ‘that they just can’t live without’ while on the road. 


The rule with loading a caravan is “if you haven’t used it in the last 12 months, you probably shouldn’t have it in your van”.


So, I suggest that you take everything out of your van and get rid of anything that you haven’t used recently. Before you put anything back in – weigh it. A set of bathroom scales will do the job in most cases. 


If you have 4 saucepans, reduce it down to 1 or two. Get appliances that are adaptable or multi use so you can leave one behind. Be ruthless. You will soon learn to adapt and there are many posts on Facebook etc with ideas to share.


For example, some caravanners cook extra at home and vacuum pack the extras in meal size. Keep them flat for easy storage and fast freezing and defrosting. In the caravan or RV the food can be simply reheated in the vacuum pack bag in some hot water with almost no washing up. The hot water can be used to make your coffee or wash up any dinner plates. Saves gas and carrying some extra pots. How many coffee cups do you really need? Is it really worth wasting fuel while carrying extra fuel in jerry cans you may never use to possibly save a couple of dollars at a small-town service station who relies on travellers for income to feed his family and stay open? Fuel is readily available all over Australia. I can understand it if travelling in the outback or off road, but the highways are well serviced.


Have a think on how you can save carrying extra stuff you can do without.

Now, how do we tell if our van is overweight?


There is a simple way to do it.


The caravan compliance plate contains the manufactures specifications for your caravan. These are legal maximum weights that must, by law be adhered to. The compliance plate is usually attached to the ‘A’ frame or attached inside the front boot.


They can be hard to read sometimes.


A Tip from Ken. Take a photo of the compliance plate with your phone and then you can enlarge it to read the numbers easily.


You will need these weights from your caravan: - 


ATM – Aggregate Trailer Mass. This is a weight in kilos that is the maximum aggregate or total weight of the caravan including all load and includes the weight on the tow ball. Total weight on wheels and jockey wheel.


GTM - Gross Trailer Mass. This is in kilos and is the maximum weight that your caravan can support on the wheels. It includes the caravan weight and all load, but it DOES NOT include the weight on the tow ball or jockey wheel.


TARE MASS - This is the weight of the caravan as it came from the manufacturer without any load added. This is before any after market extras were added like tool boxes, solar panels, extra batteries etc.


TOW BALL MASS – There may be two tow ball load figures on the compliance plate, if so the one we are interested in is the Maximum permissible ball-loading. This is the maximum weight that the caravan can have on the tow ball coupling.


The simple way – with a weighbridge.


1. Simply take your fully loaded caravan, with full water tanks and everything else you usually carry on a trip, over a weighbridge and unhook it from the tow vehicle (put it on the jockey wheel and take your tow vehicle off the weigh bridge) now note the weight. 


If it is above the ATM on the compliance plate your van is too heavy. Remove items until it is below the ATM weight.


While you are there, weigh your tow vehicle fully loaded and check its weight as per Part 1 of these articles.


2. Position your caravan so that only the jockey wheel is on the weigh bridge and caravan is level to weigh your Tow Ball Mass.


Important:- make sure the caravan is level so that the normal weight is on the jockey wheel.


Compare it to the compliance plate figure and adjust weight if needed. 


A tip from Ken. Only weighbridges that are flush with the ground can usually legally give you a tow ball weight. Weigh bridges that are raised above the ground level usually are not registered for tow ball weight as the caravan may be on an angle with wheels at ground level and jockey wheel at a different height. Check with the individual weighbridge to see what they are registered to provide.


I had a great time on a weighbridge when a local concrete plant had a shutdown. I had the weighbridge to myself for over an hour to play around with weights.

You can also purchase or hire a tow ball scale from your caravan dealer or parts supplier for about $60-70. These can be a good investment over time.


Without a weighbridge.


Now you have these weights from your compliance plate, simply take the Tare Mass away from the ATM and that will give you the maximum weight that your caravan can carry. So, we have simply take the bare caravan weight (Tare) off the maximum weight that your caravan can weight (ATM). The result is the amount of load weight that you can put in it without being overweight and illegal to have on the road.


Example: - An ATM of 2,430 kg minus a Tare of 1810 kg equals a permissible load weight of 620 kg.


2 x 80 litre water tanks at 80 kg each (160 kg) is 620kg load – 160 kg = 460 kg left for toolboxes, tools, cooking, generator etc, etc.


What is load weight? This is the weight of every aftermarket item on the caravan, plus any other items that you have put in it.


Load includes any aftermarket grey water tanks (see Ken’s tip below), solar panels, storage boxes, jerry can holders etc. It also includes all water in your water tanks (I litre = I kg), gas bottles (full plus the bottle itself), tools, cloths, food, drinks, cooking appliances etc., bedding, non-fitted chairs and tables carried in the van. It will also include any extra fuel or water in jerry cans, bicycles, firewood or generators, and boat trailers carried on the caravan.


A Tip from Ken – The water from your water tanks will transfer from your water tanks to any grey water tanks fitted as it is used for washing up, showers etc. This will not increase the weight of your caravan as no extra water has been added to the caravan, so only the full weight of the water tanks needs to be factored in and not the full weight of grey water tanks as well. The empty tank weight of any aftermarket grey water tanks fitted will however need to be considered. 


This shift in water (weight) from the water tanks to any grey water tanks will however affect the handling of your caravan. My grey water tank is filled at the rear of my caravan and the water will shift from the front water tanks to the rear grey water tank therefore adding weight to the rear of my caravan, taking weight off the front and affecting the ball weight and stability of my caravan when towing. Always empty grey water tanks as often as is practical.


The lazy way.


The lazy way to find out if you are overloaded is to wait till you are stopped by the police or Main Roads inspectors while on your holiday. They will advise you and possibly fine you and have your vehicle or vehicles banned from the road until it/they are compliant.


Otherwise, wait till you have an accident (hopefully no one is injured or killed like in Victoria recently) and see if your insurance company pays out because you were driving and/or towing an unroadworthy vehicle.


Is it worth the risk?

Part 3 – Combined weight of tow vehicle and caravan.

  In Part 1 of these articles by Truck Friendly’s Ken Wilson. I referred to the tow vehicles weight and load. 


In Part 2 I referred to the caravan weights.


These articles are also available on the Truck Friend Facebook page with other information and driving guides. www.truckfriendly.com.au


Now we look at if we load the caravan onto the tow vehicle and have one combined/connected tow rig.


There are other load ratings that I did not cover in those articles. All must be complied with to ensure your vehicles are roadworthy and legally allowed on the road.


A. Vehicle Tow Ball download rating. This is on the vehicle compliance plate and owner’s manual. It is the maximum load you can put on your vehicle tow ball as set by the vehicle manufacturer. It will usually be approx. 10% of the braked towing capacity of the vehicle and often advertised as a selling feature of the vehicle. 


Please refer to Part 1 in this series of articles on weights for more information on what is fact and advertising ‘not practical in real life’ fiction in advertising tow vehicles towing capabilities or check out the www.truckfriendly.com.au web site.


B. Vehicle Tow Bar Rating. This is found on the tow bar itself. It is the maximum load that, this tow bar can carry. It may be different to that stamped on the actual vehicles compliance plate as many tow vehicles may have after market tow bars fitted or light duty tow bars fitted by the vehicle dealer that may not be rated the same as the actual vehicles braked towing capacity or tow ball download rating. 


Having a tow bar fitted by the dealer to tow a small box trailer is very different to towing a fully loaded caravan at highway speeds.


It is important to check both of these ratings and not attach a caravan or trailer that has a tow ball download in excess of either of the above tow bar or vehicle tow ball download ratings.


A Tip from Ken. I recommend that between 10 to 12 % of the caravan ATM (total weight) is carried on the tow ball. This will help ensure correct balance and help reduce the chance of caravan sway and rollovers. Too much weight in the rear of the caravan will unbalance the van and create a pendulum effect causing the van to not recover quickly to any sudden movements or wind buffeting from passing heavy vehicles or gusty weather conditions.


Once we know that the tow vehicle is legally within all weight limits, and the caravan is within all legal weight limits as set by the manufacturer, we need to add the two together as the one tow rig.


Now that we have our caravan connected to the tow vehicle there is one last and very important weight to consider, the vehicle’s GCM or Gross Combined Mass.


The GCM is found on the vehicle’s compliance plate or owner’s manual. This is the total weight that that vehicle plus any attached trailer is legally allowed to be. So, it is the vehicle’s GVM plus the caravan’s ATM that give us the GCM or Gross Combined Mass.


In our Landcruiser 200 example in Part 1 of this series, we found the manufacturers specifications for that vehicle online. The GCM for that same Landcruiser is 6.850 kg.


With an advertised towing capacity of 3,500 kgs that means the Landcruiser should not weigh more than 3,350 kgs with all people, fuel and all cargo and added accessories fitted. 


6.850 kg GCM – 3500 kg GVM = 3,350 kg caravan ATM


So, if all weights are below those above the combined tow vehicle/caravan rig is legal. It not you will need to reduce the weight in either the tow vehicle or caravan to ensure the GCM of the tow vehicle is not exceeded. 


The tow vehicle by itself may be legal and the caravan by itself may be legal but if you have matched a large van with your tow vehicle the GCM may be exceeded.


All the above must be considered when purchasing a new or second-hand tow vehicle or caravan. Take your existing tow vehicle or van specifications with you to ensure the tow vehicle or caravan you are buying will match the unit you are keeping.


However, never tow a vehicle at maximum load. Always allow several 100 kg as a safety margin. Always have a tow vehicle that weighs more than the caravan it is towing.


Often free caravan weight checks are available in Queensland at various locations and times by Caravanning Qld and Transport and Main Roads officers. These are informative sessions. Check Caravanning Qld and other state caravanning bodies web sites for details, however at time of writing they may only be available in QLD and Victoria. They book out very fast so get in early.


There has been increased random police checks reported lately. Fortunately, they are often done with education in mind and not prosecution. This will change as caravanners are deemed to have had time to be informed. 

Don’t wait to find out if you will be taken off the road at some out of the way location. Check that your tow rig is legally roadworthy now.


Stay safe and stay Truck Friendly.


www.truckfriendly.com.au


Cheers for now

Ken.

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