I recently got a flat too....when they were balancing the wheel, they called me over to talk. The rim was bent....there is a little vibration at high speeds, but they were successfully able to balance it correctly
Hoen Xenon Match Fog Lamps
Hardwired Escort 8500-X50
S4 Matching Grille
Yokohama AVID H4S
simple put the rim on the wheel balancer and watch the run out..
you'll see real quick or can put your hand on the rim and feel any run out or bends.
a bad tire cannot balance too i've seen $300 tires from the factory impossible to balance.
I assume they used a hunter roadforce balancer. If not spend more $$ and go to a real tire shop. seriously. pep boys has them around here now. they score your rim and tire combination to give you the best possible ride.