Thanks again guys.
So today I thought I would give the trailer a once over and I got to thinking about the weight of it. I kinda weighed it before and thought it was about 260kg, Roadster is ~620kg and the trailer is plated to 950 so I thought I was ok.
Turns out that the trailer weighed in at a porky 410kg!
The runners were made of 2, 10 ft x 500mm pieces of 6mm steel tread plate so I have replaced that with some 18mm WBP ply and its down to 290kg.
So nearly 140kg of steel there. Seemed a bit overkill.
Cheers
Stot