Loud rhythmic road noise
 

Hello all,

I have a 2008 xB with 200,000 miles on it. I have been having a loud noise, particularly coming from the back, to where my passengers complained. It is rhythmic, louder around 50-55 mph and kind of choppy sounding. I have listened to see if it is different when turning left or right
but I really cannot hear any discernible difference.When the car decelerates I still have a rhythmic noise that progressively slows all the way until I stop, just not as loud. Anyway, I had my rear wheel bearings replaced at around 135,000 miles and this sound kind of reminds me of
what my bearings sounded like when they were bad then. I took my xB to the mechanic who immediately said it was my rear tires making the noise because they had "knots" in them and were cupped. So I got 2 new tires put on the front and rotated the front to the rear.
I picked up the car after hours and I still heard the noise. I took the car back the next day and I made the mechanic drive it and he said it was the rear tires.

When we got back to the shop, he felt the tires and said they too were cupped. At this point, I am starting to get suspicious but I got 2 more new tires anyway, in hopes he was right. Well, here I am 2 days later with the noise still there.
I am a single female who knows a little about cars but not enough. I am not going back to that mechanic but now I do not know who to trust. There is a reason I hear this noise and possibly a reason my tires were cupped.
Is it possible that the rear wheel bearings are bad again after around 65,000-70,000 miles?

Any suggestions? Thank you!

________________________

Have you gotten an alignment recently? If your toe is off it can create uneven wear and give you that noise you're hearing.

It is possible for aftermarket wheel bearings to fail that soon. I have heard of miata guys having to replace them yearly, but they're running their cars hard in autocross.

Is the car lowered? If so then your rear alignment is almost certain to be out. The way the rear suspension is designed on the xB causes the rear to gain more negative toe the further you lower the car. This can also cause the bearings to wear faster so it could still be either issue. Also at 200K I would check the bushings for everything in the rear as well.

I don't think bad wheel bearings are going to "cup" the tires.
This is going to get your hands dirty, but... Go out and run your hand over the top of the tires tread area, it should be round and smooth - except for the tread pattern of course
If it isn't smooth, does it feel like the tread blocks have raised edges? That is what is generally meant by cupping - cupped tires will make noise while driving, so...
Sometimes cupping can be caused by bad shock absorbers, sometimes it's just the tires. Don't buy more, just wear them out and get better tires next time - this might help
Checking the shocks can be hard, best to have a friend drive along behind you and watch the rear tires and see what happens at speed. If the tires are bouncing up and down wildy at speed, then the shocks are toast. It is worth replacing those if they have failed.

Thanks all for your replies! I did take the car in to someone who was recommended to me. He put it on the lift and spun the rear driver's side wheel for me and it wobbled badly. The diagnosis was a bad wheel bearing, which is what I thought it was from the beginning. So it has been replaced and the car is so quiet and rides much more smoothly.

He also clued me in on some other things I may want to pay attention to in the future that I will put on my maintenance and repair schedule. He said most likely the cupping I had on the tires were due to not getting them rotated and balanced on schedule and I know I did not do that like I should have. Lesson learned!

cupping on tires is not caused by not rotating and not balancing....get a new mechanic...most cupping is caused by completely shot struts or shocks or suspension bushings, but mostly shocks/struts