SimplyTire and Tires23 seem to be a couple of the more popular shops. Although the only personal experience I had was with SimplyTire and it wasn't a good one. I needed one wheel+tire and the guy said it'd be ready the next day, I show up the next day and it wasn't ready at all. So he said he'd call when it was - to this date I still haven't received the call, and it's been about 2 months now
. I'm glad I didn't pay up front for it.