2003 Merc Mountaineer AWD Grinding coming from left front tire. Tires, brakes, rotors all less than a year old, could it be a hub/bearing assembly or something different? Thanks in advance.

Check the backing plate/ dust cover on the back side of the rotors. These rust away and cause the same sound.

you probably have a seized wheel bearing/hub assembly or frozen brake caliper - you can remove the wheel hub/bearing assembly yourself in about an hour with common hand tools (an impact wrench will really speed this up) - you can rent the wheel nut removal socket at most auto parts stores - you will have to have an automotive shop with a bearing press to remove and replace the wheel bearing ($30-$60) - if the caliper is seized - replace the entire assembly (and probably the ruined brake rotors and pads)

It's either the brakes or the wheel bearing. Remove the brake rotor and check for grooves or scoring then rotate the hub assembly. You'll find a problem with one of the two. A growl that changes with vehicle speed is usually a bearing whereas brakes usually change sound as you apply low to moderate brake pressure.

Likely a bad bearing but based on the "grinding" you described, replacing the bearing may be too late and you have a bad rotor/disk.

Hello i would check your wheel bearings or sometimes called bearing hub .Jack car up prop the car with axle stands now remove your tires and rotors once removed wiggle you bearing hub left to the right your bearing hub should have minimal play one side to the other is obvious the looser play hub will be your noise you have been experiencing.most people call this road noise.

I replaced the hub bearing assembly on drivers side twice and the light stayed on and the brakes worked fine. It was the wires (visible just above the tire on the frame) that rubbed against the frame that had shorted out. It was simply repaired and clip-stripped up out of the way. The light has been off every since then.

It could be a lemon replacement hub or it could actually be the tire. Check the tires tread for irregular wear patterns. If the hub was loose prior to change this could easily cause the tire to wear in a "choppy" fashion which can also cause a rough humming sound that I have often heard customers refer to as a grinding sound.

Check the condition of the wheel bearings, front and back side if the brake rotor, and the back side of the rim. Everything should be clean, rust build-up can throw everything out of true. The hub or wheel-bearing should be tight and smooth when spun.

If same tires as before & air pressure set correctly, or as usual, a humming when swerving, or turning one way or the other or both, it's usually a pretty good indicator.

If the vehicle is made to be a AWD you cannot get it out of AWD unless you take off the front drive shaft