This is the LTSA (Land Transport Safety Authority) link to their website which specifically describes the give way rule but have a look around the rest of their site to familiarise yourself with the rules and laws in NZ
Road code - About driving
As a campervan driver, you'll probably need to be extra-courteous as your van may be a little slow up some of the bigger hills, so if you can do so safely, slow down and pull over to the left to let any queuing cars past. Don't worry if you can't though - most drivers are used to campervans on the roads and don't cause problems
