Mini Artics

Hi All,
We are fencing contractors and have a full car licence from before 1997.
I have been researching Mini Artic and getting confused with the 2 weights and the law on what is permissible.
We want to tow agricultural plant over the 3500kg that we can’t with a 4x4 and trailer, but don’t want to go the inefficient use of a tractor.
I realise that we will have to down rate a Iveco or such like chassis cab from 4,5,6.7.5 to 3.5T, put a 5th wheel on and get a trailer made, but does that mean we can tow 8250kg total or 12000kg?
Is Gross Train Weight (GTW) and Maximum Authorised Mass the same thing as we can only find 8250kg gtw but have found 12000kg mam?
What is the rule for Gross Vehicle Weight (GVW) or Gross Combined Mass (GCM) which I assume are the same and relate to the empty unit and trailer or just the mini tractor unit which I assume have to be under 7.5 tonnes?
I know Iveco do the tractor units, does anyone know of any trailer manufacturers that do a low loader type trailer.
Thanks in advance for your help

As you passed the car test before January 1st 1997 you should have code 107 on your licence, this means that you can drive a goods vehicle and trailer with a gross vehicle weight of up-to 8,250kg.

The 12,000kg you refer to is for people who have passed the category C!+E test.

The 8,250kg MAM you’re restricted to is the same as the gross train weight, the gross train weight is the maximum allowed weight of the whole vehicle, the prime mover and the trailer plus the goods being carried.

Pre 97 licence rules mean that the GVW of the vehicle and the MAM of the trailer added together MUST NOT exceed 8250kg

Legal plated weight examples with C1E 107 =
Vehicle 5.25 + trailer 3.0
Vehicle 7.5 + trailer 750kg
Vehicle 6 + trailer 2.25

I used to run a mini artic with Iveco Daily Tractor Unit (supplied by North East Truck & Van) and custom trailer (supplied by RM Trailers).

With your current 107 restriction code, you are limited to 8250GVW. If you were to take a C1+E test this would increase to 12,000kg which is far more useful.

You will also need a good vehicle operators licence.

Feel free to meet me with any questions.

Thanks for all the replies that helps backing up what my research was sort of saying. This makes me realise why all the tractors are down rated to 3.5t giving a trailer and load weight of 4750kg so will start taking to some trailer companies.
Thanks again sure I will be back to you all as we progress.
Cheers Pete