What's up with my tire?

[supermike]

My passenger side rear tire seems to make a lot of noise. I was looking at it the other day and it has kind of an odd wear pattern.

This is not my tire, but it's the kind I have, so I drew on it for a visual. The way I drew it is if you're looking at the back of the car. The backs of the individual treads on the outside edge of the tire (red area) seem to be rounded off, while the fronts of the treads (green area) seem to have almost a sharp edge. And to make things more interesting, when the weight shifts to the driver side, like when going around a right hand turn, or even if I'm going straight and I quick swerve to the right, all the humming the tire is doing completely stops until I'm going straight again. What could be going on? Would having a little toe in do this? How is it fixed?

[occasional demons]

And to make things more interesting, when the weight shifts to the driver side, like when going around a right hand turn, or even if I'm going straight and I quick swerve to the right, all the humming the tire is doing completely stops until I'm going straight again. What could be going on? Would having a little toe in do this? How is it fixed?

The humming could be the wheel bearing. The wear could also be from the wheel bearing having too much play, letting the wheel run out of spec.
Or another possiblity is the strut is blown, letting the tire bounce. when you turn it put the load on or off it changing the way it acts.
If it is the bearing you will need to remove and replace. IIRC, the nut isn't supposed to be reused. It is a nyloc style nut.
jack up the rear enough to get the tire off the ground, and see if it has any play in the bearing. try moving it from side to side, and top to bottom. Just don't put your fingers on the bottom side of the tire if there are no jackstands/blocks of wood under the frame. Prolly a good idea to use them, especially if you use the vehicle jack: not the most stable thing in the world.

[supermike]

A note on the humming, if that changes anything...

It doesn't really start until about 40 MPH, 45 is terrible, 50 is almost silent, 55 and up it just gets higher pitched with speed.

EDIT: Oh, and there must be a little vibration too, because at 45 my rear passenger speaker grill buzzes against the speaker.

[occasional demons]

Could be just from the tire. I forgot to add; tire balance can also do the same thing. Try swapping the tire to the front to see if it changes the noise in the rear. If the noise goes away/follows the tire, then have the alignment checked, and get the tires rebalanced while you're there. When they check alignment they usually will check all the components to see if it is worth aligning.

[BigMac]

It sounds to me like you're describing "cupping", which is usually caused by a bent suspension component or, rarely, by improper toe. First thing to do is get the alignment checked and corrected. To end the humming you'll likely need a new tire.

[BlackRoseRacing]

Have you checked out your rear control arm bushings?
The inner bushings where the arms bolt to the frame are common to fail causing improper rear wheel alignment

[latief]

tire feathering is what you are getting, and the noise could be from the tire itself since it is wearing out un-evenly....being bounced or dragged sideways down the road.....

check your suspension. but, first raise the rear of the car and spin the wheel. see if it is wobbling....

you either have a suspension or alignment issue. and in rare cases, some tires might have problems due to a manufacturing issue.....

don't let it go because you will wear out the rest of your new tires ....

[BigMac]

Actually, feathering occurs parallel to the center tread around the tire's circumference, like this:

The term is misused a lot; cupping is often mistakenly called feathering.

To the OP, I should've mentioned before that cupping can also be caused by a bad strut.

[supermike]

Ding ding ding! And the winner is... bad wheel bearing! I jacked it up and gave the tire a good spin, sat for like 3 minutes and listened to the noise it was making, then decided I might want to check it out. It was almost completely dry, but we couldn't get new bearings today, so we cleaned it out a little and filled it up with grease and put it back on. That should keep it until tomorrow or Monday. The difference with just the grease is phenomenal. I had no idea a bad bearing could make that much noise inside the car. Thanks for everyone's input!