If any rims are bent, they should be able to see that while spinning them on the balance machine. If balance is ok, then I'd check to see if any wheel/tire assembly is out of round. A good tire shop should be able to do this.
Another check would be to rotate the tires to different locations and see if the vibration moves around.
One other item that could cause vibration is if the drive shaft is out of balance.
Most high speed rated tires have a folded layer of nylon which will flat spot a little when the car sits and you can feel that when first driving, but that should go away after a few miles of driving. This would be an entirely separate issue from the continued vibration.