My rear tire has an oscillation. I think it’s the bead but I’m not sure how to fix it.

Yeah that what i do – deflate, spray with soapy water getting the tire bead and the bead seat of the wheel, inflate the shit outa it, drop back to normal pressure and check. If it’s one spot that’s seated incorrectly maybe you can manipulate it and roll the tire a bit by hand while inflated with just enough pressure to give it some shape. But usually inflating on the compressor to the max limit is enough when the surfaces are wet n’ soapy.