Towball down weight?

Submitted: Wednesday, Apr 23, 2003 at 18:35
ThreadID: 4530 Views:4246 Replies:7 FollowUps:3
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I have read the archives about towball down weights. I have a Jayco offroad camper, it has the kitchen at the front also the gas bottle and two jerry can holders. I have measured the towball down weight as approx 165kg. I would like to transfer the jerry can holders to the rear bumper bar, the spare wheel is also mounted on this bar.
My questions are:- Is this legal/OK to do. Has anyone done this. Would I have to strengthen the rear bar.
I have a Jeep Cherokee and the rear sags a bit when towing.
I have stabiliser bars fitted and the suspension has been renewed. Maybee placing the jerry cans at the rear will improve this and reduce the towball down weight.
Any comments will be appreciated.

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Reply By: ray91 - Wednesday, Apr 23, 2003 at 18:47

Wednesday, Apr 23, 2003 at 18:47
You should have about 10% of the trailer weight on the tow ball.If the trailer weighs 900ks then about 90ks should be on the tow ball. Move some of the weight to the back if possible.I do not think you can put jerry cans of petrol on the back though.
AnswerID: 18208

Reply By: duncs - Wednesday, Apr 23, 2003 at 19:08

Wednesday, Apr 23, 2003 at 19:08
I have heard one comment from a rego checking station that it was illeagal to carry fuel ie gas or petrol on the rear of a vehicle.

However the MQ Patrol did have an optional rack across the back that carried the spare and one jerry. That was some time ago and it may well have changed.

I would contact either the RTA or your states equivalent or your motoring body NRMA etc. for the absolute truth.

AnswerID: 18210

Follow Up By: Member - Rohan K - Monday, Apr 28, 2003 at 12:47

Monday, Apr 28, 2003 at 12:47
One of the 4WD magazines recently did an article on carrying fuel. Each state has different laws. In NSW it is illegal to carry fuel in containers on the outside of a vehicle (unprotected) but there is a suggestion that carrying it within the frame (of trailer or van) avoids this issues.

Check the regulation in the state you have registered the Jayco.Be good, or be quick.
Rohan (Sydney)
FollowupID: 11605

Reply By: herkman - Wednesday, Apr 23, 2003 at 19:32

Wednesday, Apr 23, 2003 at 19:32
My friend to carry fuel on the rear of the van, is most unwise, and I doubt if your insurance would cover such a situation.

To move the wheel to the rear of the unit, may be OK, but why do you not give us the following.

The gross weight of your unit, or if not gross the axle weight, plus what is the towball weight.

Also tell me how far back is your axle, from your towball.

Tell me how far back is the spare, where it is mounted now, and also how far back it would be if you mount it on the rear. Additionally I need the weight of the wheel.

Email that info to me at

I will then calculate, whether what you want to do is safe.

On our old 21 foot van, the action of just removing a spare wheel from the back, increased to tow ball weight by 10KGS.


Col Tigwell
AnswerID: 18212

Reply By: GOB vic - Wednesday, Apr 23, 2003 at 20:00

Wednesday, Apr 23, 2003 at 20:00
robbo same advice as above
i have 16 ft jayco offroad and am in the process of moving 1 water tank to rear of van to move some weight to back.your problem is similar to mine because jayco use the heavy drawbar on the off roaders when they weigh them empty for rego its great but when you start loading it is a real problem .you may need to move water tank to behind axle or if you have dual tanks move 1 to back of axle.problem with rear bumper jayco recomend no more than 30ks on there we were going to put push bikes on back checked it out rack manufacturer wanted a grand to strenghten back (told to get off the grass i put bikes on roof of car).
itried shifting stuff from van boot to under bed but doesnt move enough weight was at jayco today and was told no structural work to alter water tank as they can order aspecial to fit under rear .
another problem is car manufacturers max weiegt on to ball .i checked with hayman reece rep at caravan show and he said that car specs override all others so it doesnt matter how good tow hitch is its back to car you have proper tow hitch or just the light weight stabilisers sorry very hard to type with bird sitting on hand 89 nissan looking foward to august and more travelling
AnswerID: 18216

Reply By: ThePublican - Wednesday, Apr 23, 2003 at 20:21

Wednesday, Apr 23, 2003 at 20:21
Rob, 165kg sounds rather heavy for what you have,, are you weighing with jerrys full ?,,, thats 40 odd kg on the draw bar alone,,,moving them to the rear is not a Legal option in Qld at least,,10% down force onto the ball ect is the old rule of thumb for towing,,,best of my recollection has that a Jeep Cherokee is legal to 2500kg tow weight with brakes,,means upto 250kg ball weight, however if your already sagging at 165kg you seriously need to look at a weight disrtibution hitch,,new springs or Polyairs to bring her back on track.
AnswerID: 18218

Follow Up By: GOB vic - Wednesday, Apr 23, 2003 at 20:28

Wednesday, Apr 23, 2003 at 20:28
sorry publican may be legal to tow 2500kg but ball weight is set by manufacturers specs my gq can tow 2500kg but tow ball weight is only 150 .part of problem with jayco is size of draw bar used for off road units .they put all weight up front but when weighed empty are fine but filled with water and all the bits and pieces it doesnt take much to go over the ball weight89 nissan looking foward to august and more travelling
FollowupID: 11433

Follow Up By: ThePublican - Wednesday, Apr 23, 2003 at 21:12

Wednesday, Apr 23, 2003 at 21:12
GOB,,different vehicles ,different ball weights,,also depends on towbar makers specs,,GENERAL rule of thumb is 10% of allowable tow weight as ball weight,,,, just to put a cat amonst the pidgeons have a look at the legal towing weights of the latest " disco " 3500kg,,but does that mean its safe to tow a 28 ft boat weighing 3500kg with a corresponding ball weight of 350kg, think again!!!
FollowupID: 11436

Reply By: William - Wednesday, Apr 23, 2003 at 21:01

Wednesday, Apr 23, 2003 at 21:01
Ask on the caravan and campervan forum
Group home page:
AnswerID: 18224

Reply By: haze - Thursday, Apr 24, 2003 at 08:54

Thursday, Apr 24, 2003 at 08:54
To my amature thoughts there is a whole lot of mumbo jumbo assoiated with towball loading, mass distribution hitches, towing capacity etc. If one considers the towed vehicle to be a rectangular box with axle as its fulcrum supporting 90% of total mass and the remaining 10% at the front of it, it can never be tail heavy. The A frame then becomes a simple lever, the closer the coupling being to the fulcrum (axle) the greater the perceived down load, and the further away proportionally less. therefore simply extending the A frame of the Jayco 30cm. will make a considerable difference (reduction) to the ballweight but no difference to the balance of the unit. Similarly with the load distibution hitch, it cant reduce the ball weight, its already there. It simply extends the lever, and taken to an extreme will hold the rear wheels of the towing vehicle off the road given the right set of undulations. From my own observations these hitches can place conserable stress on the structure of the vehicle as well as well as premature rear tyre wear! As to published towing figures ( I have a tdi disco. as well as 75 series tray back) we went to the UK at about the time the disco was released and the number of farmers towing cattle effluent tanker tailers, heavy implements was to be seen to be believed! But they had no real ( Jap?) alternative so I expect the disco was designed appropriately. And with an articulated 4 wheel trailer ball loading doesnt come into it.
So Robbo, I would weigh the Jayco at the axle, at the A frame directly under the front, add the two together (total mass say 950kg.) then juggle your internal stuff around to give around 95kg. at the front again. Having said all of that it is also very important that your axle,hubs and tyre combinations are suited to what will be new loadings. I think some van manufacturers fudge in this area making the tow vehicle responsible for loads which should be on the van axle. hope this helps in some way. Cheers, Haze
AnswerID: 18262

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