RR tire wobbles going down the road, brakes vibrates when I apply the brakes

Check the rear rotors, and the brake pads,sounds like they are bad and have warped the rotor,s.

The tire is wobbling so that should have nothing to do with the rotors or pads, they should just grind if they were shot. It just has a really bad vibration when I apply the brakes

Sounds like you have a slipped belt in your tire. Could also be the rotors also but if you have the wobble even before you apply your brake its the tire. Do this test run your hand over the tread of the bad tire if you feel a hump in the tire that is your problem.

Also make sure the wheel lugs are tight.

You need to check the wheel bearing, lug nuts and the physical condition of the wheel. If all are okay replace the tire.