getting tires mounted

*noobie alert* I plan on getting a s2000 soon, and would like to know where I should be going to get tires mounted: I see on the tirerack site where they will mount the high point of the tire to the low point of the rim if you buy a set from them, but what if I already have the rims? Will a Discount Tire do this? Who do I go to for this kind of treatment? Am I missing something here? (hey, I'm a noobie to sports cars, so I'm starting from scratch)