I have heard you can get some deals on line. For my money I use Discount Tire (I think they are called American Tire some places). This chain is so much on customer service. They keep your information on the computer, and they check it store to store. They will always check your tires for free and put air in them. They have fixed a nail for me on tires I did not buy there. Bottom line, the prices are good, they will give you service after the sale and they are quite pleasant for a large chain? Who do you think is the go to source for new tires.
I tend to notice with tires it's best to always shop around. Every time I need new tires I go to everywhere around me. I never find that the same place is the cheapest like ever! I prefer Mr. Tire but only because my friend works there and he is awesome and gives everyone amazing customer service. I also love how as a company they will price match any competitor and then beat there price by 5% as well!