I took my Ranger in for an oil change and tire rotation at Meineke.  It has
13,400 miles on it and is 2WD.  It had 18 miles on it when I got it from the
dealer.

This was the first time that I had the tires rotated.  I'm sure it was over
due but I didn't think it was by much.  The mechanic called me out to the
garage and showed me that the all 4 tires were cupping and said that it was
because of defective shocks.  He said that the front tires were the worst
but the back tires were in trouble too.  He knew that it didn't have many
miles on it and suggested that I raise hell with the dealer to have the
shocks replaced before it ate up my tires any more.  He did rotate them left
to right so as to leave the better tires on the back for traction.

I called the service desk at the dealer and he told me that the cupping
would not be caused by bad shocks and that it had to be because of
misalignment or lack of rotation.   He said that the front wheels had to be
misaligned and the back tires had been rotated so they were also showing the
wear also.  I know that this is not the case since they had never been
rotated before.

So here are my questions to you guys:

Do bad shocks lead to cupping?

How does lack of rotation cause cupping on the back tires when it has a
fixed axle that needs no alignment?

Thanks in advance for your opinions.