Only when vehicle is in motion do I hear constant humming noise like the windows are down, gets louder each day, have been told it is the tires and also wheel bearings, which one could it be?

 

Going to need a trained ear to drive and listen.. I would blame tires, as we rarely if ever see bearings on CM..

How many miles ? Lay palm of hand on tread and move in same direction as tread rolls down road, feel lumps/uneven traed blocks/patterns of tread ?