In British English, tyre is the rubber ring around a wheel and tire is a verb meaning to become weary. American English spells the wheel part tire too, so the split is a British habit. Memory hook: a tyre is what you check on a car, but you tire after a long walk.
The core difference
In British English, tyre is the wheel part and tire is the verb meaning to grow weary.
- tyre — the rubber ring fitted around a wheel: He checked the tyre pressure before the long drive.
- tire — to become weary, or to lose interest: She began to tire after the third hour of hiking.
How to tell them apart
British writers use two spellings to keep the meanings separate: tyre for the noun on a wheel and tire for the verb. American writers use tire for both, so if you are writing for a UK audience, stick with tyre for the car part.
The mix-up mostly happens when a UK writer types tire for a flat wheel, or when someone reads American text and assumes the spelling is an error. Check the sense: if it is about a wheel, it is tyre in British English.
