humming noise in rear wheels

when i get up to about 40-50mph, theres a prominent humming noise comin from my rear end...dealership said it was the tires...but i just got my new rims/tires on, and it still does it...not as loud, but still doin it...is it wheel bearings possibly? or a rotor? also...my alignment is just fine, but if i take my hands on the wheel...it shakes...anyone help me out? i've only got 25,000 miles on it...thanks guys

On my car it also made a popping pop sometimes. It was fixed when my technicians did something with the rear trailing arm, but I couldn't make out the rest of the stuff he wrote. It would seem Manybrews is Mitsubishi's only tech that is literate.