my 2010 xc60 is wearing the drivers side rear tire unevenly...cupping on the inside edge of tire....what could be causing this uneven wear?

 

have you had the car in for an alignment? take it to a pro that will insplect for bent or worn suspension components. At this point you also may want to consider replacing the tires (depending on wear you may need to do a pair or all four after the alignment has been addressed).