Waste tyres can leach heavy metals.
Sixty thousand tonnes of used tyre waste is created each year in New Zealand.
A new recycling plant that will process half of that waste each year - turning it into a fuel source - has opened in Auckland.
Three million car tyres will be processed at the recycling plant each year, shredded in a purpose-built machine and broken into 15 millimetre chips that can be used as a fuel source. Read more in the Newshub article.
This Waste Management World article speaks of a similar initiative in Wellington.
Leave them with the tyre company, when you get new ones.
Can be made into planter boxes, tyre swings, retaining walls.
Can be cut in half and used underneath a 'sea-saw'.
Tractor tyres make great sandpits.