road noise from the rear

when ever I get up to speeds above 35 i hear a loud, almost like tire noise from the rear of the car, both sides.

Ive heard several suggestions but wanted to ask for advice before I got it looked at. I was told it could be the wheel bearings, but it doesnt grind and you cant hear it at low speeds so i didnt think that was it. I was also told it was just normal tire noise, but its gotten louder over time it seemed. Any suggestions would be appreciated.

Note: Steering wheel does not shake. and no abnormal wear on tires.

thanx in advance