A 21 foot van (interior dimensions) is probably about 8 metres coupling to rear. Typically that would be about 4.5-5.0M from the coupling to centre of the axles, then 3.0-3.5M to the rear. So the positioning of the water tanks 1.5M (4'6") from the axles centre will mean close to one third of the water weight will be on the towball.
180L of water would mean 50-60kg difference between full and empty on the towball. That is quite substantial. Water tanks centred at the axle is the best design, but it depends on whether Windsor (or the previous owner) chose to position the tanks that far forwards because it benefited from more weight on the towball.
Moving the tanks should be a good idea, but knowing the actual van weights when laden for travel would confirm or deny that idea. Taking actual measurements rather than my guesswork wouild also help. If moving the tanks makes the towball weight too light it could affect the handling. The weight of the tanks and fittings also should be considered, although probably not significant.
-- Edited by Are We Lost on Friday 26th of July 2024 12:01:12 PM
It will reduce yaw inertia (google it if you don't understand what it is). That will significantly improve stability.
All significant weight should be as close to the axles and as far from the ends of a van as possible.
Cheers,
Peter