Honestly, this looks like the sort of place that you might get shot at if you stopped, but it's one of the best tire places I've ever gone to. My family has been going to M&M for years.
The owner is a nice guy, and their prices are very fair for both new and used tires. Once I got a used tire and it went flat on me 2 days later, they replaced it with another used tire in better condition. The workers are all friendly, and very courteous. The owner doesn't allow them to use foul language around customers, I've seen him pull guys aside and tell them if they can't speak properly, they can find another job.
I would call ahead to make sure they have your size in stock, especially if you're getting a used tire.