How do they calculate towing weights limits?

Hi ben_gv3, Here is what I have heard about the possible reason that manufacturers don't seem to have the answers to your questions.

Australia & New Zealand are big on towing trailers, it is not that common in most other country's. Vehicle manufacturers don't really want to be bothered with all the testing etc. to cover any litigation that could follow if an accident or warranty claim should occur if one of their vehicles was towing at the time. It is easier to give very conservative loose guidelines rather then go through all the possible testing to find the 'real' limits.

Don't know if the above is true but I think it probably is.

some manufacturers prey to work out towing capacity and other manufacturers set safe and reliable performance capacity for towing. 3T on Navara or 2.8T on Hilux ridiculous like 2.5T on Terracant.

no one mentioned brakes! Both for the vehicle and trailer (depending on weight). They have to be up to the task also.

Leroy

They a load of crap, just sales hype and it works. A mate of mine just brought a Navara partly because it can tow 3t, only way it could tow that is downhill with a tail wind.

I've always been of the opinion that the weight of the towing vehicle should exceed the loaded weight of the van or trailer to be towed.
If the trailer or van is to be towed 'off road' then the difference between the two should be even more in favour of the towing vehicle.
This is purely a personal opinion based on my experiences of towing all over Oz during the last 30 years.
There is no substitute for vehicle mass when things go cock-eyed, I've seen plenty of people come unstuck when the van or trailer decides it wants to lead.
Having just completed a trip into the outback I am amazed at the size of the vans that people hook up to vehicles especially mid sized vehicles like Prado's, Pajero's etc, never mind the soft roaders like Xtrails pulling 2 tonne+ of van! It might be legal but it looks like an accident waiting to happen to me.

To me, the towing capacties specified by the manufactures make no sense whatsoever. I think they just make them up too. I'm sure I would have towed over my pathetic legal limit of 1500kg on my reece hitch with the 3.0L diesel, but I've never had any power/handling/braking issues. I have never weighed the loads I have towed, but when you load a furniture trailer up that 900kg tare you've got to be pushing the 1500kg boundry, same when towing a dingo with orga and other accessories. But hey, each to their own. I can't see how a lighter, crappyier plastic pathfinder can legally tow 3500kg and mine can only tow 1500kg, doesn't make sense to me....

ben_gv3

With our Patrol, the same motor was 3.5 t for manual and 2.5 t for auto. The guy at the Nissan dealership couldn't understand the difference and said out auto would handle the load fine (he was not selling us the car either - we took in in to get gauges fitted). We suspect the auto may not have sufficient emergency braking capacity should all other systems fail when rolling down off a mountain. I still believe in the principal of having the tow vehicle outweigh the trailer for safety.

With all the difference between makes, perhaps they draw the weights out of a hat? It does not seem to be related to performance when towing.