Thread: Tow Ball Download weight confusion with state legal

Originally Posted by apilko

BUT if you minus the 200kg off the GVW then that only leaves you 3,040kg - then if you minus the weight of the car with fuel and accessories (2702kg) you end up with a remaining payload of 338kg - NOW 338kg payload is final for passengers and luggage, BUT if that payload has to account for the 290kg of TBD then you're only left with 48kg - not even enough for a driver!

Thats youre mistake right there..

the 200kg comes out of the GVM, if you then take it out of the payload you've removed the weight twice.

and even if it was, as its a landrover that 48kg is more than enough for the driver. Unless they've changed it every landrover manual I've ever read through includes an allowance for the driver, tank of fuel, spare tyre and a sundry of other things, this is why if you ever weigh bridge it you'll probably find that you can get more into a 750KG net rated landrover than you can a 1T anything else....

there was a stage where a certain company was advertising 1t utes, problem was the payload did not include, the tray, a tank of fuel, the spare tyre, the driver or anything else over the very basic pov pack, hell if you bought it in the auto version it wasnt even a true 1T vehicle as a bare cab/chassis.

Hi,

It is a challenging topic and one that the manual and supplements and published specifications for the D4 don’t really make crystal clear. I looked into this too, to try to make sure that if I loaded the D4 and Van that it would be within limits. What I came to might be some help.

It seems to me that the critical limit when considering towing with the D4 is not so much the GVM as the rear axle capacity. The maximum rear axle capacity for the D4 is 1855kg. When considering the mass on the rear axle the tow ball load must be considered. It is important to realise that because the tow ball hangs off the back, the load on the rear axle to be included is greater than the actual weight. Typically, the load share carried by the rear axle is 1.5 times the weight of the ball (it can vary).

If you have 280kg of ball weight, then the extra load carried by the rear axle is probably 420kg. If you have a lightly laden D4, with some fuel and a couple of people, let’s say that is 2,800kg. Add 420kg and you end up with about 1820kg on the rear axle. You can’t really go much more in the back (35kg) without over-loading the rear axle capacity.

It seems to me that the numbers that the OP came up with look about right. It is hard not to overload the rear axle, depending on how much extra stuff is on/in the car with a large van. The LR supplement suggests that a target tow ball mass of about 7% is the suggested minimum. I agree having looked at the limits on the rear axle. Lighter ball load is better. And in light of the GVM reduction that the OP noted for >250kg ball weight, a ball weight of 250kg would seem to be a good target. Oh and 7% of 3,500kg is 245kg.

Just one of many views on this.

And no one can explain or identify the source of the science behind '10%' rule that leads people to putting 350kgs of weight on the ball to drag something along at 90 degrees to the 'force'.

I have a genuine LR plated RRC towbar, max ball weight 120kg, max tow weight 4,000kg.

DL

And no one can explain or identify the source of the science behind '10%' rule that leads people to putting 350kgs of weight on the ball to drag something along at 90 degrees to the 'force'.

I have a genuine LR plated RRC towbar, max ball weight 120kg, max tow weight 4,000kg.

DL

Originally Posted by 350RRC

And no one can explain or identify the source of the science behind '10%' rule that leads people to putting 350kgs of weight on the ball to drag something along at 90 degrees to the 'force'.

I have a genuine LR plated RRC towbar, max ball weight 120kg, max tow weight 4,000kg.

DL

And when one of the mobs out there did a random weigh in, they found all those who claimed to be running at 10% were often closer to 5-7%.

Overseas 5-7% is the norm, just another Aussie thing I guess.

Perhaps it's a case of making it all a lot harder than it is, try this.
Load the van and car as you would if you were setting off on a trip, the whole nine yards.
Find a public weigh bridge or private one that is weighs and measures certified.
Roll onto the weigh bridge with the van attached and get the operator to record front axle mass, then whole vehicle, ( you can calculate rear axle mass from this), then car and van combined (this gives you GCM) and finally van axle group, and you have GTM. (Gross Trailer Mass - the load on the van axles not including tow ball mass)
Then check these values against the vehicle and caravan specifications and adjust as necessary.
At the end of the day this is what is important from your safety, road legal and insurance perspective.
Peter

Its a complicated topic. My take on it is to focus on 3 things. Tow ball weight, trailer weight and total train weight.

Tow ball weight is highly variable. For example:

I have a D4 and a rather large boat. On the weigh bridge the boat with 400L of fuel and 100L of water and all the gear weighs 3160kg. Obviously its rare I would tow it around with that much fuel in it.
When I first got the boat it towed terribly - bouncing around and it felt like it was lifting the back of the car. So I bought a tow ball weight measuring device and the TBW was only 60kg! I made quite a few adjustments to where the boat was positioned on the trailer and where all the weight was and increased the TBW to 160kg. This tows very nicely now. I checked this both with the gadget and also at the weigh bridge:
1 boat attached to car both on bridge = 5830kg
2. Boat attached to car but car off the bridge 3000kg
3. Boat unattached to car and boat on bridge 3160kg.

So my rear axel weight is fine, and my total train weight is fine.

So I would take your own measurements and buy a simple measuring device - you might be surprised.

Four towing weight examples - explained! - YouTube