That's exactally what I did at Wal-Mart. I ordered them on a Friday and they called me the following Tuesday and told me the tires were in. I drove the boat up to the Wal-Mart, a little over a mile from my house, and looked around in the fishing tackle dept for about 1/2 an hour while they mounted & balanced them. The even used a torque wrench to tighten the lugs nuts and then another guy came around and made sure the lugs were torqued to the proper specs. They had the low price $54 + 7 or 8 bucks apiece for mounting, lifetime balance, and road hazard protection. The road hazard warranty came in handy the very first time I drove on them when I backed the boat back in the driveway I backed over the metal chock I had left laying in my driveway. It caught the tire right in the sidewall resulting in what I believe is called a catastrophic rapid deflation. Wal-Mart replaced the tire without even pointing and giggling...no charge at all.
The only whimper I had was they inflated the new tires to only 35#psi. Those guys just aren't used to putting 50#'s in a 13" tire, so watch that.
I'm really not pushing Wal-Mart because I own stock in them or because I'm some sort of Wallyword geek, but they really did have the best deal going.
Harpo