The word tire is predominantly used in American English to refer to the round rubber cushion that fits around a wheel rim and is inflated to cushion the vehicle as it moves. Its usage is specific to the context of vehicles and is strictly considered a noun within this context. Whenever referring to this vehicle component in America or for an American audience, tire is the appropriate choice.

Similarly, tyre is used within British, Australian, and other Commonwealth nations' English vernacular to denote the same rubber cushion for a wheel. Its usage mirrors that of tire in American English, as a noun referring to the part of a vehicle that makes contact with the road. When writing or speaking in these regions, tyre is the term you should use.

Ultimately, tire and tyre represent geographical differences in spelling rather than any functional distinction. Tire is the preferred term in American English, while tyre is favored in British English and in many Commonwealth countries. Understanding these differences is crucial for proper usage in written and spoken language, ensuring both clarity and regional appropriateness.