Towing capacity vs weight

G'day Lizcantow

See www.campertrailers.org under Tech Tips / Australian Towing Regulations

Cheers
John

Hi Liz,

You have probably opened up a can of worms here as there are differing views on this.

Here is what my opinion is.
The specified total trailer weight of a vehicle is the maximum you can tow in “good conditions”. With my Landcruiser this is 3500 Kg. However I choose NOT to tow at the limit of my vehicle for long distances. I have a self imposed limit of about 85% of the vehicles maximum (about 3000 kg). In my view this gives me a “buffer” of safety should I strike adverse road conditions unexpectedly (eg on recent trip came across cattle on road after rounding a bend and had to brake to a standstill suddenly).

Yes you can legally tow a trailer greater weight than your tow vehicle. The maximum loaded weight of my Landcruiser is 3300kg. So I could legally tow a trailer 200kg heavier than my tow vehicle. However I CHOOSE not to. I am of the view that it is safer to have the tow vehicle heavier than the trailer. Toyota recommend that if the trailer is heavier than the tow vehicle a sway control device should be used.
Generally you have very few kilometres of road that to me would be classified as “good conditions”….much of our outback roads have dips, broken edges, potholes, narrow bitumen etc as well as the possibility of wet conditions. So in my personal view it is dangerous to tow to the vehicles maximum capacity for long distances (I am happy to tow a 3500kg boat a few kms to the local boat ramp).

When ordering a new off road caravan recently we specifically wanted one less than 3000kg ATM. It came in at about 2750kg. But this was a self imposed limit by choice. Over the past few years in our travels we have seen 3 jack-knifed van accidents. They do happen. My view is you can reduce the risk of this happening by towing less weight than the manufacturers specified maximum and by keeping the tow vehicle heavier than the trailer.

Cheers

Liz,

No need to make fun as this subject is a can of worms.

My understanding is that a vehicle is designed with components that will enable it to work with a Gross Combined Mass (GCM)

So there is 3 measurements that need to be followed. Gross combined Mass (GCM) - Gross Vehicle Mass (GVM) and Braked towing capacity.

So using my 100 series

GCM = 6680kg total (This can never change even with a GVM upgrade). Vehicle and towed mass.

Gross Vehicle Mass (GVM) is made up of Kerb weight (2413 kg) and Payload capacity (767 kg). So GVM is 3180kg.

GCM is made up by adding GVM = 3180 kg and braked towing capacity 3500kg
________________________________________________________

So depending on vehicle fit out (GXL 767 kg to Sahara 516 kg) the payload will change.

A GVM upgrade, in my case up by 500kg - 3180 to 3680 my towing capability is reduced by 500 kg to fit within the GCM.

All that said, I would limit my towing to 75% of the tow vehicle and not run at maximum capacity........... but then again a B-Double a prime mover weighs a fraction of what it pulls and stops, same as a road train.


(By the way, the BT-50 is an anomaly as the quoted figures do not seem to add up!)

GCM can BE CHANGED.

Your wrong on that.
an 80 series can be upped from 2980 gvm to 3350 gvm, and the GCM was upgraded too.
the 80 series was 2500kg rated upped to 3500kg towing capacity.
been done with a canberra engineer.

soo what someone says isnt always the bible.
find out for yourself with the local authorities than taking someones word for it.

yes i would.
i would make sure their is a decent load on the rear axle of the vehicle to tow the max capacity, it helps in the wet!!

and especialy with any suspension lift, i would definatly recommend getting the brakes checked to see that the LPSV, load proportioning s valve is working when you carry some weight in the rear.

i recently was fully loaded, over 3tonne, in an industrial area, driving about 30k' an hour and had to brake, road was recently dry for some time, and it rained, soo super greasy, the fronts locked up as they do, and i kept them locked up, as usualy im going quicker, i slid about 10mtrs overshoot the t intersection, and came to a stop finaly.
realised the rear brakes never came on!!
soo got around to the LPSV and raised it about 20mm, off the diff.
took it down a dirt road, doing 40 to 50, braked hard, fronts locked, then unlocked via my foot pressure on the pedal, and the rears worked a treat.

no worries towing a full van, just make sure their is some weight on the vehicle to pull it up.
or cross winds to throw the vehicle around, or simply do the safest thing and reduce speed.

Hi Lizcantow,

With all those numbers I am starting to get a head ache. Manufacturers are only interested in selling cars so their ratings tend to be a bit optomistic at times I think.

I reckon Wamuranman is spot on with his formula.

IMHO, common sense and the laws of physics say that the tug must be 15-20% heavier than the van/trailer to maintain control in all but the worst conditions.

What is the kerb weight of the volvo's?

Classic example of thinking to much about something that is not needed to be known and then trying to figure out the calculations of how the many factory engineers came to their conclusion......

All vehicles have advertised maximum weights for the vehicle by it's self and if towing.

If you exceed these weights your overloaded and if you stay under these weights your safe.

All you have to ask is "can my vehicle carry and tow this weight...... it's going to be yes or no..... there is no maybe's or?????....... it's yes or no.

Maybe the vehicle manufactures should look on the forums for there next lot of engineers......

There are many things that come into the equation.... Axle loadings, axle capacities, suspension, chassis, brakes, drive train, engine cooling and many more....

I don't think you have opened a can of worms at all. Your main query was about the general rule of not towing more weight than the tow vehicle.

To answer this questiion, there is no such rule.

People have different ideas on what weight you can or can't tow but it still comes down to what the manufacturer states you can tow legally not some general rule, but do agree that you need to allow for road conditions etc.
Chris