In response to the OP's question, wheel "hop" to me is axle wrapping, it sounds like that isn't what is happening to you.
That said, if this issue occurs at any speed, I would almost guarantee its not the tyres being out of balance.
It is possible that they are out of round. Is it definitely coming from the rear axle? If so, I would be checking your wheel bearings.
If you can't be sure if its coming from the front or the rear axle (it can be surprisingly hard to tell at times!), check the play in all your front end components.