I just went through this about a month ago.
Paid GST & PST ( Ontario 8% ).
No duty, as the rims & tires were considered " Auto parts ". No argument from me, I prefer to play dumb. They didn't ask where my rims ( Borbet - Germany ) were made.
Beware !!!!!, if you have any issues warranty ) with the goods, it can be a real PITA, to get stuff back & forth across the border.
Btw., cost me $ 60.00, to get the tires re-balanced. Just so you know.