This place you won't really come across it if you don't know it exists because it's off a side street and not in plain sight. Located west of Dixie and east of Hurontario off of a side street (Hydro) off of Lakeshore it's not in plain sight.
They have a handful of bays to perform auto service but as their name states their main focus seems to be on tires. They sell all sorts of tires and they have wheels too. There's a computer in the back to put your car and whatever wheels you want to see on it just so you can visualize what your car would like like with custom aftermarket rims etc.
I went to Extreme to get a tire replaced. I had a nail and a bulge on the inside of my driver side rear tire that I had probably been driving around with for some time. I wanted to get this resolved the same day because the condition of the tire was unsafe and could blow at any time.
My size is not common (215 / 18) but they had the exact same one I had in stock. It was early in the afternoon but they normally close at 1pm. I had called asking first if they had my tire in stock and they did and the advisor told me they closed at 3pm (on a Saturday) so I got in just after 2pm.
They were able to give me a good price on my tire based on what I paid for them previously. Of course there's tax and environmental fee but I was lucky to find Xtreme and also lucky they had stock of my size because many places I notice don't.