ChevyGuy· Premium Member
This puzzles me. Rust tends to suggest lack of use - yet the pads are worn out. My guess is that the caliper on that side is stuck. It used to stick in a way that caused excessive wear, but now it's stuck in a position such that it no longer engages.My rear right brake disc is in bad shape, rusted, and the brake pads are almost finished. The rear left side looks great, I would say those pads look almost like new, same for the brake disc.
Rear brakes tend to lead a very easy life. They'll last much longer than the front. At 50,000 miles, I don't think the left side is loafing - but the right side has been dragging.