Wobble At 50-60 Mph - "cupped" Tires?

[batta]

my 02 530i sport was taken in to the local bmw dealer for a balance & alignment because it was pulling a bit to the left.
When I picked it up, they said they had to rotate the tires as well and I would get a wobble between 50-60mph that will eventually wear out. ok, this made sense to me because of the rotation i guess. They balanced it out, placing various little metal blocks on the rim part of the wheel.
months and many miles went by and the wobble remained (accelerating and braking through 50-60mph). I took it back in and they told me my tires were "cupped". The Dunlop P235/45ZR17 are relativly new with plenty of tread.
Why did I not have this issue before I originally brought it in?
How common is this and what causes it?

Any input appreciated.

Mike

[Murphyslaw]

Hi Mike,

Don't know if this is the same as your problem but it sounds very similar. Do you find the steering wheel shakes viscously through that speed zone when braking?

I have the same problem with my 540. Some people have suggested as the engine is so heavy that it could be the lower control arm bushes, they tend to wear rather quickly on my car (apparantly). I have had other issues with the cars reliability until recently so have not looked into getting this resolved, however I have been told you can put upgraded bushes in place which should wear better and last longer.

Let me know how you get on and I will report back when I get mine changed (sooner rather than later I hope)

All the best

Iain

[batta]

Thanks Iain.

Yes, the wheel does shake through that speed zone. The car has only 38k miles on it, so it would suprise me if something like that wore out...and my engine is not nearly as heavy as your 8, but I guess if the bushing are bad it wont matter. I did a serach on news groups for "cupped wheels" and found an enormous amount of posts with similar descriptions. I'll keep you updated.

Thanks again,

Mike

Originally posted by Murphyslaw@Nov 9 2004, 05:17 AM
Hi Mike,

Don't know if this is the same as your problem but it sounds very similar. Do you find the steering wheel shakes viscously through that speed zone when braking?

I have the same problem with my 540. Some people have suggested as the engine is so heavy that it could be the lower control arm bushes, they tend to wear rather quickly on my car (apparantly). I have had other issues with the cars reliability until recently so have not looked into getting this resolved, however I have been told you can put upgraded bushes in place which should wear better and last longer.

Let me know how you get on and I will report back when I get mine changed (sooner rather than later I hope)

All the best

Iain

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[CosmosBlack]

If your tires are cupped, meaning it wears on the center of the tire...
you need to put more psi on them. This happens usually with soft compound high performance tires. If the pressure is low, when the tires warm up, the tire expands and this causes the center to bulge, hence having more contact on the road surface. Now, when the car is parked, the tires cool down and the center contracts back to its original position. So it looks cupped...and you wonder if it's cupped, how did the wear occur???

Put more air pressure in the tires, that way when the rubber gets warm and expand, the higher air pressure will "hold" the shape of the tire better, thus maintaining a flatter contact with the road surface.

Manufacturer's recommended psi is probably only good for regular tires. Mine says 31 front and 35 rear...My mechanic recommends 33 front and 41 rear. It would mean a harder ride over rough surfaces.
I am still experimenting this on my new tires...so I have yet to see if my mechanic's theory is correct. Oh by the way...my last set of tires were all cupped...Yokohama AVS ES100...very soft and noisy tires...HORRIBLE!