I understand your preference for a Canadian company, but Crappy Tire shouldn't be using that as an excuse to give poor customer service.
If your receipt says you have 60 days for a refund or exchange, you could try going to the manager or even the owner to get what you were promised in writing. You could try giving the names of the staff, too. Maybe he/she will care (but maybe not.)
You could also try taking the plant to different Crappy Tire stores, since their policy is to allow returns at any store.
Unfortunately, the staff at Crappy Tire stores have a long list of excuses to refuse routine returns. Some will even say, "refund or exchange? The store gets to decide which it will be".
Sad to say, there are many stories like yours on this web site, and others.
Some Crappy Clerk started posting on this thread yesterday:
https://www.canadiantiresucks.net/employees-speak-out/49-customer-service-rep-8.html#post4956. He claims to know the secret "code 55" and "cod 50" procedures a store can use to get a credit for things customers return. Maybe you can post something there, and learn the magic words to use when you ask for a refund?
Unfortunately, the best solution is to take all your business to other retailers, who all have better policies, and actually follow them.
Too bad this chain is going down hill so fast with their horrible policies and poor service.
Their slogan should be, "Bring on your money - then go away".