Tires: CUPPING OF TIRES, passenger car tires, bridgestone tires

Question
The Hyundai auto dealership says the undulating appearance of the tires is cupping caused by faulty Bridgestone tires.  The tire dealership where I bought four new tires approximately 13,000 miles ago says the cupping is caused by misalignment.  I have had them rotated once and the vast majority of the usage is on interstates.  Can misalignment cause cupping or will misalignment cause irregular wear only?  How do you distinguish between the two if my shocks feel like they are working well?

Thanks for the help.

Ben

Answer
Ben,

It takes lots of experience to distinguish between "Cupping" and "Irregular Wear" in modern radial passenger car tires and, frankly, most normally experienced people do not have it.  Irregular wear gets called cupping on a regular basis.

Since radial tires are fairly insensitive to the wear caused by imbalance and bad shocks, but fairly sensitive to alignment induced wear, you're probably safe assuming the alignment is the problem.