Mazda Repair: Humming noise in a 2003 Mazda Protege 5, mazda protege 5, wheel bearing noise

Question
I have a 2003 Mazda Protege 5 that makes a strange humming noise when I reach 40 mph.  The sound can still be heard at 50 mph, then the engine noise drowns it out. It has a manual transmission if that helps.  

Answer
Hi Kathleen , Thanks for asking.
 There are many things that can make strange noises when reaching highways speeds. But the 2 most common ones are, wheel bearing noise and tire noise. If your wheel alignment is out enough, it can cause the tires to srcub the ground and give you a humming noise at higher speeds. With a worn wheel bearing it can cause the same noise and slightly go away when you turn the vehicle on the hiway. Have a technician check those two items out. If it is the tires you will probably have to change the tires now and do a 4 wheel thrust alignment. If is a wheel bearing you will have to cahnge the wheel bearing wich can get fairly pricey! But check with a Madza dealership (if yous till have warranty) because i know they will cover that.
good luck
Chris P