Does it sound like wheel bearings or the rear axle?
Rumbling noise in rear wheel. Noise speeds up with mph what does this sound like on 2005 Chrysler Crossfire
Have you visually checked your tires for any wear pattern on the inside edges? They may be 'cupping' , and that can cause a noise like a wheel bearing. Just another option to check besides the two you already mentioned.
Got a new tires because of the noise. No visual wear after 300 miles. Noise still the same.
THEN , YES , AS YOU STATED ORIGINALLY , HAVE REAR BEARINGS ETC. CHECKED.