Not all brake pads have wear indicators and many times even if they do some bozo "mechanic" could have put them on the outer position instead of on the inner position where they belong as the inner pads always wear out sooner. If you see metal chips on the inside of the wheel you're grinding the rotor away because the brake pad material is gone. There's always a chance you have a bad wheel bearing. If you drive at 30 mph and veer left and right in your lane the grinding noise should go away in one direction and get louder in the other direction. Mechanics check brakes for free, go to the dealer for your next oil change. The factory mechanics always check the car over for free to up sell more work and the brakes are the first thing they check while the oil is draining. They will show you the problems and explain why it needs to be repaired. Good mechanics never have a problem showing a customer why they recommend they should spend their money maintaining their ride.

Remove the wheels and check the BRAKE pad thickness by looking down through the caliper inspection holes on the back side of the calipers.

If the noise gets louder as you drive faster without touching the brake petal, more than likely you have a bad wheel bearing.

Oh right... the "high pitch" noise other cars make is when the "wear indicator" is working correctly.

It sounds like your brake pads are completely worn and you need to have them replaced ASAP.

agreed with these guys, check your brake pads.. check that its not harmed the rotor already... wheel bearings generaly very loud grinding sound.. jack the vehicle up from the frame so no pressure on the tire and shake it around... bad wheel bearing usualy has a lot of give. the tire assymbly will just flop around easly if its as bad as it sounds.... if that's the problem. as they said check the breaks while your checking wheel bearing. one or the other is the issue.

if u only hear it with windows down pacifically listening for the sound then if its a wheel bearing I doubt its terribly bad yet but will be soon haha.

brakes, tire bad, wheel bearing, will have to have it checked by a mechanic to nail it down

Yesterday, my 99 Saturn sl1 started having a grinding noise when I'm driving, which occurs almost always while I'm moving but never while I'm stopped. The pitch of the noise changes as I speed up and when I use the brakes.

It appears likely to be related to my brakes, but I didn't at all hear a squeaking nose before this when breaking and I've driven with my windows down and radio off several times before this. Also, during the last couple of days, I've been driving in the desert southwest if that matters.

The noise is only coming from my front drivers side tire; my other front tire isn't making any noise. The noise isn't really a high pitch when compared to the noise I've heard other cars make when their brake pads are going bad, and it's not all that loud.