Tire balancing is the second hardest thing in the world to do properly right after open heart surgery.
I just got my summer tires put on by a local toyota dealership since they had a hunter roadforce machine. Paid a decent penny for mounting and balancing. Sure enough, after getting the job done, I hit 60mph and boom, steering wheel shimmy and rear end wobble.
I asked before I left if there were any issues and if the tires balanced nicely and the tech told me it was fine with no issues.
I know its not my suspension since my winter tires drove amazingly smooth with no vibrating.
I swear, tire balancing will be the death of me.