2001 Other Plymouth Models

I HAVE A PLYMOUTH NEON,RECENTLY IT STARTED MAKING A HUMMING NOISE WHILE DRIVING AT ANY SPEED.I REPLACED THE FRONT STRUTS,HAD AN ALLAINMENT DONE PUT FOUR NEW TIRES ON,PUT NEW REAR BREAK DRUMS ON AND IT STILL SOUNDS AS THOUGH I'M DRIVING A TRUCK WITH 38"TIRES NOT BALLANCED ON IT.IT SOUNDS LIKE ITS COMING FROM THE REAR OF THE CAR.