That link says 8 March 2015.
Edit: I think this is the correct link.
http://www.eventfinda.co.nz/2016/the-wellington-truck-and-transport-show/upper-hutt?utm_campaign=also-visited-events&utm_medium=click-through&utm_source=2015%2Fthe-great-wellington-truck-show%2Fupper-hutt
It says Sunday March 13, 2016. I'm keen.