Vehicle Towing Capacity

[Rob M]

I have been trying to find out how vehicle manufacturers determine the towing capacity of a vehicle. Despite my research I cannot find any standard formula or rules that govern this.
Does each manufacturer determine for themselves or are there a standard set of parameters that are used internationally.
How accurate are the towing specifications provided by manufacturers as it is factor we take into account when deciding on the tow vehicle.
My interest comes from seeing some relatively small SUV's with a 3 tonne towing capacity when some others are rated at 2.5 even though they seem to have a larger body etc.
Why are some manual vehicles rated at a higher towing capacity than the same auto models?
Hopefully someone on the forum who has a high level of knowledge may be able to provide answers.
Cheers,
Rob

[Cruiser 105Tvan]

Dunno bout the Level of ?
Manufacturers determine the vehicle capacity for towing.
It has to do with the braking capacity, the Axle assembly weight carrying capacity, strength of bodywork/resistance to bending etc.
The Manufacturers have Engineers that work all of it out for 'em.

Basically 'The bigger the tow vehicle, the more it can tow/carry.'

[peter_mcc]

I suspect that the marketing department has a fairly large input as well... either "don't make it bigger than 2500kgs or nobody will buy the bigger one" (Prado) or "it has to be at least as big as the competitors" (all the utes).

[weonatvan]

Manufacturers take many factors into consideration before plucking a figure out of the air, (power, vehicle weight, size of brakes etc) which may also differ from one market to another. For example Australia is considered a "hot climate" country which could/will reduce their tow rating, along with shortened service intervals then say NZ.

On a side note, a dual cab 4x4 ute with a towing capacity of 3,500kg is about as handy and usable as a hip pocket in a singlet. With a gross combination mass (GCM) of 6,000kg only leaves 2,500kg (which will also include tow ball down force) for a loaded DC ready to tow. Considering that mine is pushing 2,700kg (gross vehicle mass (GVM) 3,040kg) before my bum goes on the seat (no gear) then a realistic 2,500kg towing figure comes into play.

This is where the politics of "one-up-manship" over an opposition manufacturer comes into play which is a advertisers/salesman marketing ploy to sell their product and has absolutely nothing to do with what is realistically and legally achievable in the real world.

There have been many articles written in fourby mags about this farcical topic. 

But, at the end of the day, what would I know. lol     

[Cruiser 105Tvan]

Yep.
Cheers Dave.

Robert.

[Rob M]

Thanks for the insight Dave. I suspected such factors may be at play but was hoping that there might be a precise formula.
Cheers
Rob

[Rolcar52]

 So really the only way to be safely legal is to tow with something like a 79 series dual cab Land cruiser, GVM 3300 kg and  CVM6800 kg. All the dual cab utes are claiming unrealistic figures.  I drive a 2010 dual cab ute loaded with what I take camping it weight's 2680 Kgs so add the ball weight and its overweight before we sit in it, so the solution is empty the car and shed 400Kg, so no spares, camping gear, recovery gear, basically carry nothing and it's legal. Like many people I was unaware of of the regulations only started looking into it because we were thinking of upgrading to a Topaz after all we can tow 2250 kg, so we thought. There is no way it would be legal with the current vehicle, so check out some of the new ones that claim 3500 Kg do the sums and they are legal but only just with this 3500 Kg being very much a fairy tale. Once being weighted used to fairly rare but not so now, so being found illegal in Birdsville could be very expensive as would being in a serious accident and having no insurance.   

[Eelezy]

Yep..thank goodness I have a 76 series Landcruiser  no matter what they try to tell, you,  all the bigger 4wds are much better options for towing than what is being touted by the car companies with the small 4cyl diesel engines working hard all the time. However, even the mighty cruisers can end up easily over gmv with all the extras added...
Chris

[Harry Lissimore]

So Rolf, wouldn't the landcruiser still have the same problem?  You would have to factor in the Tare Mass of the car and if it was about 2800 kg, then you would only have 500 kg for fuel, people, tools etc and ball wt of the trailer.  Most normal vehicles only have a payload of about 500 - 700 kg.  Take off 250 kg ball wt, 2 people (160 kg), full tank of fuel (50kg)  and there's only about 50 - 250 kg of tools, extra tyre, recovery gear you can carry.

With my Isuzu MU-X, the payload is 700 kg. When I'm loaded up with all the gear, with the Topaz on the back, I have calculated that  I'm overloaded by about 12 cans of beer, but when I've gone about 40 Ks, the weight gets back to legal. The Isuzu can legally tow 3000 kg, the ball wt is the limiting factor as in influences the GVM. The GCM is 5750 kg, GVM is 2750 KG.  The other limiting factor is the GVM of the Topaz - 2250 kg from memory, and I'm at the max with that as well, otherwise I would transfer some of the cars payload to the Topaz.

[Phil G]

When I'm loaded up with all the gear, with the Topaz on the back, I have calculated that  I'm overloaded by about 12 cans of beer, but when I've gone about 40 Ks, the weight gets back to legal.

I guess that means your fuel consumption is 30 cans per 100k - that's a slab in an hour which can't be legal???

[Rolcar52]

Harry,
The cruiser with a  GVM of 3300Kg and a CVM of 6800Kg bolts it in. The thing is we buy a Tvan or Topaz to go just about anywhere,then set the vehicle up so we don't get stuck, the trouble is in my case anyway that once all the necessary accessories, fuel, recovery gear,tools, spares and camping gear, Tvan, and passengers are loaded vehicle GVM has been exceeded, as would most Dual cab utes i think. I'm 3000 Kg when loaded ready to go. I have Old Man Emu 400Kg springs fitted in the rear not sure what the front is this lifts the vehicle the legal 50mm. I'm in the process of getting a GVM upgrade to 3300Kg at the moment so hopefully wont need to worry after that. I'd like a land cruiser but not keen on the fuel consumption.

[Cruiser 105Tvan]

Rolf, you do realize that your combined mass doesn't increase when you upgrade the tug?
Your extra capacity is robbed out of your towed capacity.

Unless, of course, if you go nuts and put your hi-lux body on a Cruiser chassis and running gear. 

[Rolcar52]

Yeh Cruiser,
I know, also doesn't increase the manufacturers towing capacity just legalizes the Hilux for 3300Kg GVM. At the moment it only has a CVM of 2810 Kg once i set it up with Bull bar, Winch, Canopy, long Range tank,Roof rack,Drifta Draws, tools,recovery gear, it was 2680 Kg, so once i added 2 bums and the Tvan it was over GVM.     

[Cruiser 105Tvan]

Ok Rolf good work.
Just as well you get about with the Tvan and not a Topaz.