cupped is probably the word I wanted, must have been hungry when I posted.
the point is, if the shocks are shot, the tires will be eaten for dinner.
this summer my original 2003 shocks gave up the ghost, (with only 140,000 miles on them) i drove from VA to Cape Cod then to see my son in Scotia NY, and stopped at the local firestone. ( I have a lifetime balance rotate and allignment) they balanced and rotated the tires, said the alignment was fine, and said the ride problem was out of balance tires. on the ride from Scotia NY back to VA, the ride was ok at first, but was back to the vibration well before I got home. now I have four tires which hum at me, with the inside edges which have the first row of tread sculpted into wedges.
the firestone place did say I needed shocks, but I did not want to pay the the grand or so they estimated. ( included sway bar links too) If they had leveled with me that the shocks were eating the tires, i at least would have had them not rotate, so I would have two nasty tires, instead of four. if the salesperson/service writer was on the ball, I might have let them do the install, but now I just know they are incompetent.
I did change the shocks, struts, and a few other items (having had lots of fun in the process) now the ride is ok, but the tires still sing. they have lots of tread, so it is hard for me to change them just for the noise. perhaps next year.