Spot the Hidden Canadian is a fun game: they think they can pass for Unitedstatesians, but there are Signs. (It's said that Peter Jennings's TelePrompTer has the word "lieutenant" written as "lootenant", in order to remind him not to say "leftenant" and destroy, quelle horreur!, the illusion that he's One Of Us.)
If someone writes "tire center", they're probably American; if they write "tyre centre", they might be British. But if they write "tire centre", that marks the Canadian. (When a Brit read an earlier version of this post, he enquired whether a "tire centre" was a place where people go in order to become less energetic and more sleepy.)
When speaking, there are three things to look for: the "eh?", Canadian Raising ("writer" and "rider" sound different; "spider" and "inside her" don't quite rhyme, and so much for Miss Muffet), and the rounded British/Bostonian pronunciation of short "o" as in "hot" and "pot". None alone is infallible: all three together? Canadian.
We do but jest, poison in jest, no offense i'th' world.