I have a 2010 silverado 1500 4x4. I have 33s mud tires. I have a bad vibration and noise that seems to get worse with speed and the longer I drive. I know it isn't my tires because the sound and vibration used to not be this bad. The tread is wearing evenly too, and I get regular alignments, rotations and balances. I took it to a mechanic and they said they could not hear any noise over the sound of the tires even though I told them the tires used to never be that loud (only ran it on the rack, didn't test drive it). I recently had my ball bearings replaced and I know all of the suspensions and steering parts are good. After I went to the mechanic I went home and jacked up the front of my truck (in neutral and parking brake off) and spun my wheels, they spun freely and without noise. Then I did the same with the back, the back left wheel spun freely but had a soft, intermittent grinding noise, the back right wheel was harder to spin and had a louder more constant grinding noise. Is this the wheel bearings or something else? (back wheels have drum brakes). Any help would be greatly appreciated, it is insanely aggravating! And I'm going on a long trip soon and don't want anything to get worse.

 

hats a hard one to diagnose without hearing it. try a different mechanic and see if they can find it

 

I just really don't have the money to see another mechanic and get the problem fixed, I'm just a broke college student . This one was willing to look at it free of charge. If it is wheel bearings on the rear it's at least $200 a side and most mechanics around here charge about $80 to look at it. There definitely noise that sounds kinda like a wheel bearing, I guess they just can't distinguish the tire noise from that like I can since I'm used to what the tires should sound like

 

This is one of the most difficult things to diagnose.