Originally Posted by
SSSimon
In either case though, you are not allowed to exceed the 9000 kg GVM/GCM whatever is the correct term for your jurisdiction. So with the correct 5th wheel set up it seems that you could go to the max 5.5t trailer weight, allowing 3.5t for the vehicle and 1t of fuel, supplies, gear, etc.
While the vehicle is capable of towing such a weight - and is rated for it in the US, it is not rated for it in Aus. The max rated limit in Aus is 4.5t, whether it was a 5th wheel or conventional hitch.
The same trucks in the states are rated to 12000lbs (20,000lb GCM) for both conventional or 5th wheel hitches.
That said, you would be pretty stiffed if a cop pulled you over and new the tow rating for them when they were new.
Originally Posted by
Dags
Alot more can be pulled as a fifth wheeler because they're set up as a prime mover. So in effect you can put the vehicles carrying capacity on the turntable, pivotball because it's shared between the front and rear axle, and the balance of the weight is on the wheels of the trailer, as stated, up to 9 ton or whatever.
Even with my 6 wheels on the Effie I am still only legal to PULL 4500kg's, and thats a combination of the heavy towbar, and the twin rail chassis, so I'm a bit envious of an F truck that can pull 4500kg's just using factory options.
A tow rating is based off a lot of things.
This gives you a good idea:
Tow Ratings Finally Pass the Sniff Test - The Society of Automotive Engineers (SAE) - Automobile Magazine
In these model trucks, it is the powertrain that is the limiting factor - more specifically the (auto) transmission. Go over its 20,000lb GCM and it is likely to overheat when going up a grade. So in this case it didn't matter whether you had a 5th wheel or a conventional trailer - it was rated for the same.
The newer trucks are limited by the handling, even with a good weight dist. hitch you can't get as much weight over the front axle. That said, Tim - one of the other site admins here - tows about 22,000 lbs with a conventional hitch with his F350.
