did you get an alignment after getting two tires done? did they swap tires to the rear or are the rears tires the same as before? (even swap sides?)

if the wheel bearing or anything were going bad, the noise wouldnt have just started, loudly it would have come gradual..

unever tire wear getting sent to the back of the car, by say, putting the best of the 4 tires on the reat, and putting the two new on front, if the rears are worn, feathered, etc they could make noise, also the front tires could make noise to depending on what you bough and the alignment..

but as exodus asked, what does it sound like? swap the tires front to back to (same side) and see if the noise changes, or goes away.. it almost sounds like an unbalance tire or bad alignment.