Hello Bopeep,
From the description of what you have done I suspect you haven't understood how the regulations must be applied and your results are significantly in error. To have any chance of providing meaningful results with which to assess your particular outfit, you must adhere to the correct loading and measuring procedures.
To be legal you must be able to get the centre of the loaded tow ball to settle between 350 and 420mm vertically above horizontal ground.
The problem is: Can that be achieved with every possible trailer that can be towed? The important factor is the nose load. The EU specify that the nose load of any trailer must impose a minimum of 25kg on the tow-ball. The maximum is limited by the design specification of the tow-bar assembly.
You may wish to tow this light trailer with just the driver in the car and no additional luggage or passengers. So for the outfit to be compliant with EU regs, the ball height should settle between 350 and 420mm with just the driver in the car and a 25Kg load on the ball hitch.
At the other extreme with the nose load at the maximum allowable for the hitch, and the car fully loaded (including the nose load) the tow-ball height should still remain within the Regulations 350 to 420 window.
If the tow-ball does not remain within this height window under tall possible legal combinations of trailers and car loads, then the car/towbar is not compliant with the regulations.
The fitters of the tow-bar assembly are required to to ensure the fitting complies with the regulations. - and ultimately the driver must not drive an outfit that does not comply with the regulations.
From the description of what you have done I suspect you haven't understood how the regulations must be applied and your results are significantly in error. To have any chance of providing meaningful results with which to assess your particular outfit, you must adhere to the correct loading and measuring procedures.
To be legal you must be able to get the centre of the loaded tow ball to settle between 350 and 420mm vertically above horizontal ground.
The problem is: Can that be achieved with every possible trailer that can be towed? The important factor is the nose load. The EU specify that the nose load of any trailer must impose a minimum of 25kg on the tow-ball. The maximum is limited by the design specification of the tow-bar assembly.
You may wish to tow this light trailer with just the driver in the car and no additional luggage or passengers. So for the outfit to be compliant with EU regs, the ball height should settle between 350 and 420mm with just the driver in the car and a 25Kg load on the ball hitch.
At the other extreme with the nose load at the maximum allowable for the hitch, and the car fully loaded (including the nose load) the tow-ball height should still remain within the Regulations 350 to 420 window.
If the tow-ball does not remain within this height window under tall possible legal combinations of trailers and car loads, then the car/towbar is not compliant with the regulations.
The fitters of the tow-bar assembly are required to to ensure the fitting complies with the regulations. - and ultimately the driver must not drive an outfit that does not comply with the regulations.