I just bought my 2nd Maxima day before yesterday. This is a 2014 with approx 119k miles and no engine or transmission problems that I can tell. I got it two days ago and when I got on the highway it kept getting louder and louder. Yes, the brakes need checking because there's a slight Creek during reverse, but this loud roaring humming thing that almost feels like it will pop my ears from what feels like slight pressure+volume, it's coming from the rear and gets louder with speed. Bearings? Tires? Thoughts? Experience? Thank you.

 

I can tell from my office that the sound is both the tires and wheel bearings. Replace all four tires with a brand name tire, mounted and balanced by a reputable shop that can also check to see if your wheels are out of round or bent.

Replace both rear wheel bearings and have your brakes repaired.