I have a 1998 blazer and i drive it 20 miles one way to work everyday doing about 70 mph constantly for 15 to 20 mins and as i get off the highway as the rpm's drop it starts to make like a humming almost grinding kind of sound and will not stop until i slow down to about 2 or 3 mph. if i bring the rpm's up i dont hear the noise above about 2000. if i brake a few times on the way home i general do not hear the noise. Can anyone help me?

 

is it coming from the engine or the tires?

 

i cant really tell. i thought it was the tires but i just put new tires on it two days ago the noise changed a little but did not go away. i cant actually get out of the car and listen to it because it starts on the highway and stops when i stop.

 

but you can jack up the front end and wiggle your tires to see how much play they have.

I think your going to have to try narrow it down a bit further for us to try help.