You may have a bent wheel, or a broken belt in a tire. Look for a small knot on the tires. That would be a sign of a broken belt. That will save you some money. As far as the bent rim, only a competent tire shop can find that out for you.

Bent wheels, bad alignment, broken belts, they all don't wait until you go sixty miles per hour to show up. And the second wheel balance making it worse kind of points to a very bad wheel balance job. The only other thing I can think of that might make the balance change like that is something inside the tire rolling around and that is unlikely. Take it back to where you got the tires balanced and talk to the service writer, most shops will do what ever is needed to make it right.

If all of the suspension is OK and the rims are OK the problem you report is a bad tire. It is in need to be replaced. Having some ride in another car. NOT THE DRIVER OF THE OTHER CAR. A passenger. This person can watch each of the four tires one at a time. If the tire is bouncing like it was on bad road, that is the bad tire. No much past buying a new one. However, tires come with warranties. Check on that. It is a manufacturing defect. There will be an adjustment in price based on the wear on the tire. Good luck.

It could be an alignment problem or a damaged suspension part.

I ve recently gotten tire balancing done twice. My car was first vibrating at speeds of 55-70 + and now I've got the tire balancing done the second time and it vibrates at 20mph now. It seemed to be running better before balancing them. Please help and what I can tell the service shop so he won't rape me for money .

Thanks