I recently had uneven wear on my tires and.

I recently had uneven wear on my tires and started hearing a noise that I thought was caused by the bad tires, sort of a humming that increased as the speed increased. I had the tires replaced and the alignment checked but I still get the humming noise. If it was a bearing, wouldn't it be more of a screetch or metal to metal sound? I am going to take it to my mechanic but I am trying to figure out what it could be. Any help would be appreciated.