everytime i reach about 50ish mph, i start hearing a constant humming that sounds like it's coming from the left side of the engine compartment. it will get louder until about 60mph and then by the time i reach 75ish, i can't really hear it anymore. has anyone heard of this or have an idea what it might be?

the noise is constant whether i'm accelerating, cruising, or braking, so it seems to be directly correlated to my road speed. my tires were bald when i bought my car and i was hoping that was it, but i put new tires on a few weeks ago and the noise hasn't gone away. if fact, with the old tires (which were a little smaller), the mph range that i heard the noise was more like 40-65mph.

any ideas??

 

You have a bad wheel bearing.

 

Yup...that'd be it. Do you hear a fast-paced pulsating or vibrating "thump-thump-thump-thump....." along with it? Mine did that, but yep, my vote is on the bearing. Should run about $250 parts & labor.