You don't need to register vehicles used only on a private road. (A private road means a road or place formed on private land by the owner of that land.)
With the exception of the above, using an unregistered vehicle on a road is an offence. However if you are fined for using an unregistered vehicle you will have a defence if your vehicle is:
an official vehicle of a visiting military force
a vehicle being operated on a road that is closed to ordinary vehicular traffic
a motor vehicle that is being temporarily towed without use of its own power
a trailer attached to a tractor, traction engine, forklift, a self-propelled machine that's designed for specialist industrial purposes
a trailer attached to a self-propelled machine that is designed for agricultural purposes
a trailer designed exclusively for agricultural operations and used on a road only when proceeding to or from a farm or when being inspected, serviced or repaired
a trailer attached to an exempted vehicle as defined in the Land Transport Management (Apportionment and Refund of Excise Duty and Excise–Equivalent Duty) Regulations 2004
an overseas visitors vehicle. An overseas visitor’s vehicle is one that's registered overseas and will be in New Zealand for less than 18 months. For more information about overseas visitors vehicles, see Importing a vehicle temporarily.
Factsheet 27: Exempt vehicles from registration and licensing [PDF, 58 KB]
