Hi i am very new at cars and any suggestion will help.
I drive altima 2003 3.5 and everything was fine till yesterday when i started to hear this very low humming noise when i hit 40mph and up, faster i got louder and faster the sound. I didnt hear this noise during my previous drives. I think the noise is comming more from the back then the front and i checked all the tires to see if anything was rubbing against it, but didnt find anything I also checked my breaks and it was fine. Any suggestions will be much appreciated. thanks

 

could be a wheel bearing