Towing Capacity

[flyfisher63]

Hi I am looking at purchasing a camper trailer and I am a bit confused with all the towing capacities etc, I own a Great Wall X200 towing capacity is 1700kg does this mean that I cannot tow a camper greater than 1700kg, also does this mean if I add food, water, extra battery, clothing, bedding, fishing gear, fridge ect etc, when this added into the camper and the weight is over 1700kg can I still tow it or is the tow weigh just the camper by itself, not going full off road, just up to Cape York along tracks, Barrington Tops etc, any other info re towing would be appreciated I checked out the info in Tech Tips and am still a bit confused if someone can explain in simple layman's terms please.

[armbrup]

does this mean that I cannot tow a camper greater than 1700kg, also does this mean if I add food,

It means that you cannot tow the trailer loaded up if the trailer weighs more than 1700Kg loaded up.
There will be 2 or 3 weights on the trailer plate
1 the tare weight which is supposedly what it weighs empty.
2 the GTM or gross trailer mass which means loaded.
You also have another weight to think about and that is the towball weight. The towbar should have a printed plate on it which has the maximum ball weight on it.

I have seen many camper trailers where the tare weight is pure fiction, so if you really want to know the weight you should take it over a weighbridge empty and weigh everything you put in, including water.

Another thing you should consider is that only one maker Land Rover advises that maximum weights should be halved for off road but as 4WD Australia recently pointed out none of the Japs do that and bent chassis are quite common on Japanese utes. Now the Peninsula development Road can be really corrugated so do not underestimate its roughness. The bloke in Coen makes a very good living out of repairing overloaded 4x4s and camper trailers.

There is another weight that you have to be aware of and that is the Gross Combination Mass or GCM. This should not be a problem for you unless you load the car to the gunnels as well as have the trailer right up on 1700Kg, which I hope you will not as IMHO it would be foolhardy.
Regards Philip A
BTW, do not believe the camper trailer maker on this, as many can lie with a straight face.

[robcaz]

While it may all sound a little complicated, you do need to get all the capacities right or you could void your vehicle warranty or worse still void your insurance in an accident.

Yes that is correct, you cannot tow a camper weighing more than the vehicle manufacturers recommended GTM (Gross Trailer Mass), the towbar capacity, or the less of the two.

Ball weight should be keep under the vehicle manufacturers limit too.

Also be aware that some manufacturers are weighing the trailer only & stamping this weight on the VIN plate before the canvas tent or other accessories are added.



In this example the TARE or unloaded weight is said to be 450kg, when in fact the combined weight of the trailer & camper top is actually 720kg. This only allows a 30kg payload before brakes are required by law, however the camper trailer owner thinks they have a huge weight limit of 300kg to load their camper up with gear.

Don't take the word of the manufacturer if you suspect the camper to be heavier than it is. Ask for the camper to be run over a public weighbridge before purchase so you can check the weight & the suitability to your vehicles towing limits.

As a rule of thumb the ball weight is around 10% to 15% of the trailers weight which will give the trailer a good balance & tracking characteristics.

[jw2170]

Also remember to check the Camper Trailer very carefully

A trailer with brakes and only a 40mm square axle will have a GTM of only 1000kgs.
Upgrade to a 45mm axle and you may only go up to 1400kgs or 1700kgs?..

For example, some of the Black Series campers with independent suspension are only showing a GVM? of 1400kgs. [maybe this should be GTM?]

[robcaz]

A trailer has GTM, Gross Trailer Mass while a vehicle has GVM Gross Vehicle Mass.

The size of the axle, the design load of the bearings & the design load of the spindle machining give an axle its maximum load capacity.

As an example a 45 square axle with Holden bearings may have a load rating of 1300kg where as a similar size axle with Falcon bearings may have a load capacity of 1800kg.

A Vehicle Components 45mm square axle with their SLM bearing series is rated at 2000kg. This is because they use a Ford inner bearing as the inner & a Holden inner bearing as the outer.

Axles, bearings & loads from Vehicle Components http://www.campertrailers.org/axles_bearings.htm

[jw2170]

Great information, Rob.

I did not realize the bearings could make so much difference....

This is always a "vague" topic.

[armbrup]

We must have scared the OP away!
It's nice to know outcomes.
Regards Philip A

[flyfisher63]

Hi OK got it now I have looked at camper trailers and noted that the campers have a GTM (gross trailer mass) I presume this is the maximum weight it can be loaded to with fuel water food etc etc, and my vehicle has a 1700kg tow limit, so the camper fully loaded must not go above 1700kg, I have been looking at keeping the trailer fully loaded at about 1500kg, and the ball weight would be about 150kg, GW recommend not going above 170kg and my Hayman Reese has a tow ball weight limit of 3500lbs? but am looking at changing to accommodate a poly block hitch, and would a weight distribution system be of benefit, would it be of benefit for me to up the suspension on my GW X200 looking at a 50mm lift kit and torsion bar, I have also been lead to believe that a airbag suspension would help in the towing and ride of the vehicle?

[armbrup]

Hayman Reese has a tow ball weight limit of 3500lbs?

That refers to the maximum amount that can be towed, and refers to the square tongue.

This has no relationship to the amount of downward force that can be put on the towbar which you say is 170Kg.

Weight equalizer bars are only for onroad use and will put great stress on your car on dirt roads, especially like the Cape York Development road which has numerous dips. You also should not need them with a camper trailer.

Fitting airbags can be helpful in preventing excessive bottoming of the rear suspension. IMHO you should load up with the trailer and do a trial trip and see how the car feels, and observe whether it bottoms excessively or sags at the back with the trailer on. You should maybe check the ball weight of the trailer as especially with full jerry cans on the aframe they can get easily over 200Kg and that will disqualify that trailer for your car.

A polyblock coupling is a good idea if you plan to go on tracks with large humps etc but probably unnecessary if you plan to stay on formed dirt roads, and they can be a bugger to couple and uncouple. I would recommend what I have replaced my polyblock with and that is a McHitch Uniglide coupling .
Regards Philip A

[robcaz]

Hi flyfisher,

I have added a photo to my article with an explanation to weight limits so I hope that explains it better http://www.campertrailers.org/balancing_act.htm

You are correct with your calcs, 1700kg is the maximum weight of the trailer you can tow & a maximum 170kg ball weight.

Depending on how soft your rear coils are & your payload will determine the amount of sag in the rear end. Don't forget the trailers ball weight is added to the vehicles payload. With a ball weight of 150kg, two people, luggage, a tank of fuel etc, you will not have much left of your 475kg payload.

PolyAir or Coil-Rite airbags inserted into your rear coils will help with levelling your vehicle when you have the trailer looked up. We used PolyAir's in the Patrol for twenty years & now have Coil-Rite in the Jeep for the last four years. Best thing is you get a great ride around town when not towing without getting a harsh ride from heavy duty coils that are set up for towing.

They are easy to use, measure the height of your towbar & then pump the air bags up to say 30lb. Hook your trailer up & let air out to get the towbar height back to measurement before you hooked the trailer up. After that initial time you will know what the pressure is. When not towing you can let them down to 4lb.

I have never used a weight distribution hitch so perhaps someone may fill you in with their use as we head off road & they are not suited to 4wding.