The Trikke 8.5” wheel sets are available in single, double or 3 packs and can be used on the the following models: T67cs (Blue or Orange); T7 Kids or T7 Fitness; T8 models later than 2005. If your Trikke T8 is a polished aluminum (silver) it is an older 2001-2004 model, aka T8v1 or T8v2, and will NOT mount the air tires.