Speedway New Zealand has released a long term Calendar for the New Zealand Champs, GP titles and North Island and South Island Champs.
New Zealand Champs:
Grand Prix Titles:
North Island Champs:
South Island Champs:
I would like to add that there is hopefully going to be a new dirt racing game sometime soon but your help is needed: https://www.kickstarter.com/projects/bigant/big-ant-dirt-track-racing?ref=card