Why is the British version of "tire" is "tyre"?
Is there a reason they call diaper nappys? or elevators lifts? It's the queen's English. It differs from us american folk.

In British English both spellings are correct, but both words mean
totally different things.
In all of the English speaking world, the word tire when used as a
verb means to become exhausted/sleepy.
In Britain and many other Commonwealth nations, the word tyre is a
noun, it's the word we use for the outer rubber part of a vehicle
wheel.  For example, a bicycle tyre, or a car tyre.  In the USA the
word tyre is spelt tire.
Here are a couple of examples of British English usage: Since the
onset of her illness, she tires very easily. I find that I tire quite
easily these days. The car tyres need to be replaced. The bicycle tyre
has a puncture.
In American English, all of the sentences above would use the spelling
&quot;tire&quot;.

Source
This may or may not be a question for the English language and Usage stack though.