Rear wheel pulsing. Not rotor.

I had that pulsing feeling when braking in my 90 teg. Plus in the morning when it was cold when backing out of my space I heard this horrible low toned hum as the rotors turned. I found it to be the rear driver’s rotor. I replaced both rears with new Brembos. When I installed the driver’s side I noticed slight pulsing drag when spinning the rotor around by hand, like the NEW rotor needed to br resurfaced. Now the pulsing when I brake is completely gone, but I still get the low hum, almost like whale sounds when backing out in the morning. What should I be looking for as the problem? Should I replace the whole rear wheel assembly?

wheel barring maybe?

change your wheel bearing.

Cool, thanks.