Where can I get motorcycle tires changed cheapest?

What kind of bike do you have and how urgent is the tire change? Because the answer varies quite a bit depending on that.

Generally, independent shops tend to be cheaper than official dealerships. If you go to a neighborhood shop with a good reputation, you typically pay less than at the brand's agency. The downside is you don't always know the quality of the service or whether they're selling you low-quality tires disguised as good ones. There's also the option of buying tires online (there are several sites that sell them at competitive prices) and taking them yourself to a shop to have them installed, which sometimes ends up cheaper than buying and installing in the same place.

My recommendation is to get quotes from at least two or three places: a nearby shop, another one someone you trust recommends, and check out what online prices look like. Pay attention to what brand and model of tire they're offering you at each place, because it's not the same to switch to generic tires as to something decent. Sometimes the price difference is minimal but the durability is completely different. In my experience, it's worth spending a bit more if it's somewhere you already know does good work.