probable causes of cupping wear:
loose wheel bearings
mismounted tire/ wheel assembly
out of balance wheel assembly
worn bearings, shocks, springs or other suspension components
inconsistent inflation (10 PSI or greater)
out of all of these, BALANCE!. bent rims can be fixed, but if they wobble sideways you can have cupping. alignment check will not hurt, but you would have to have insane toe, and weak shocks.