Tyres and wheels
https://vehicleinspection.nzta.govt.nz/virms/in-service-wof-and-cof/tractors/tyres-wheels-and-hubs/tyres-and-wheels
: Construction , in relation to a tyre, means a) for a pneumatic tyre, the type of carcass (including ply orientation and ply rating or load index) b) for any other tyre, characteristics relating to size, shape and material. Pneumatic tyre means a tyre that, when in use, is inflated by air or gas introduced from time to time under pressure so as to enclose under normal inflation a cushion of air or gas forming altogether at least half of the total area of an average cross-section of a tyre so