rear tires are cupping out on the inside tread, is this an alignment
problem or some other mechanical problem, thanks for you responce

 

If they are the OE Goodyear RTS, mine did as well. At the time I did a general search on google and found many others complaining of the same with those tires. Have you rotated your tires recently? If not, that and balancing would be good places to start. If you have never gotten an alignment it might be worth the peace of mind to rule that out. A side note, Discount Tire bought my old tires and applied a credit to my new tires, even with easily noticeable cupping, so if you are thinking about new tires keep that in mind.