In Australia it's spelled "tire" as far as I know. I've never really seen the spelling "tyre" used here before, hence invalidating the claim that any country that relies on British spelling all use the same spellings for words.
Given you can't see points, hartror is correct, and here's a collection of tyre retailer names as evidence
Kmart Tyre & Auto Service
Welshpool Tyre Service
Berry's Tyres
Fremantle Tyrepower
Ian Diffen World of Tyres & Mufflers
West State Tyre Service
National Tyres
(you get the idea)
1) Are you Australian? (sub question, were you born Australian?)
2) What state/territory do you live in?
Because every state and territory I've lived in, it's been tyre. I've never seen tire used except by non-native speakers.