2004 Optra rear caliper sticky

I have a 04 optra and sometime when it is not used for a while my rear caliper sticks and the tire won't even go around. Can anyone help me with this. Thanks in advance.

This can happen when the seal around your caliper piston cracks or tears. Water gets into the piston and seizes it up. Right now it's probably at the point where after the vehicle has been driven for a while and the brakes are used, it frees up the piston. Eventually, however, this piston will completely seize and cause your pad to rub against the rotor which will eventually eat all of the pad material away and destroy your rotor and/or boil your brake fluid from the friction. You can either try to rebuild the caliper with new seals and possibly a new piston OR you can buy a new caliper from a store like NAPA. Just make sure you change the pad on the other side as well.