I had a set of BF Goodrich tires years ago. They were great, except one went out of round on me. Took it in and they did the same thing. Told me my rim was bent. While on the machine they told me what I was seeing was the rim, but all that was moving was the tire. They refused to replace it. Went to a tire dealer just down the road, had them look at it. They came back and said the tire had failed. To say the least, I don't do business with the other shop anymore, even though the Assistant Manager was a good friend at the time.
No tire or rim from the mfg. is perfectly balanced. When a new tire is mounted to your rim, if the gods are against you that day, all of the disproportionate weight ends up on the same side. A good tech will see that. I had this happen at America's tire once. I happened to see the tire and wheel when they were putting it on the truck with what looked like a 1/2 lb. of weights on one side. I went and got the manager. He had them rotate the tire on the wheel and rebalance and all was well then. A good balance man knows when things aren't right. Luckily the manager was sharp enough to know what I was talking about. The store I went to is a good store but sh** happens some days.