** copied from another thread, but I thought it was more relevant here **
This is what I have discovered regarding downgrading GVM in NSW & ACT.
Basically if the truck was built with the option of two GVM versions for the exact same truck from the manufacturer (such as NPS250@4.495Tonne & NPS300@6.000Tonne) then all that is required is an engineers report and a new compliance plate fitted. Quotes for engineers certificate range from $695 to $1800 for the excact same report.
If the truck was made only in one version such as 6Tonne, then a physical modification is required to the vehicle that redistributes the load to the rear axles differently to when it was manufactured (either upgrading or downgrading).
I know this makes no sense when downgrading, and this definition is is a bit cryptic, and no one at the RTA technical division or the engineers could ellaborate on this clearly either.
Perhaps a torsion free setup would have been acceptable, but I did not think to ask this at the time.
See:
http://www.rta.nsw.gov.au/registrati...oads/vib29.pdf