My car (2003 Honda CR-V, 54000 mile) started to make "sssss" sound from the rear-driver side wheel while driving, but not so severe at the moment. I checked the wheel and found that the pad was worn out: metal to disk. The other three pads are a little bit (2-3mm) left over. I visited some franchise mechanic shop and was told that the pads, rotors, and calipers need to be replaced. But I'm wondering about the caliper replacement. Do you think that my car makes "ssss" sound when brakes not being applied, which possibly means a stuck piston, so the calipers also need to be replaced? Would you please share your insights for this issue with me? I got brake fluid flushed every 3 years, for your information. I think that some air in the side caused by poor recent bleeding might cause the symptom or it might be a normal situation, which means the caliper itself is fine. What do you think about this issue and what do you suggest for a repair? Thank you!