I have a 2005 Cobalt LS and it has been making this sound ever since I bought it.At about 55-60 MPH it makes this humming noise whenever the wheel rotates around.Now immediately I thought it was a wheel hub so I jacked all of the wheels up and tugged on them to make sure there was no movement otherwise It would have been a wheel hub.But I tugged on all of them and rotated them and no noise and no movement.

I still think a wheel hub is about to go out but Im just wondering if it could be anything else.Thanks in advance

 

Check the fender where it meets the A pillar, had a issue like that with the 06 and it was the fender
slightly touching the Apillar,to check jam a peice of cardboard under that point and go for a test drive.

Check to see also that you have all the plugs in that support the fender liner and bumper.(black push in things)

 

Did you buy the car new? Mine started making a similar noise around 40K and slowly kept getting louder for the next 30K miles. I thought it was tire noise, which it sounds similar. I also pulled on the wheels and hubs. And then I finally replaced a hub assembly and the noise got quieter. Then I replaced the one on the other side. Now the car is quiet driving down the highway - just like new.