The outside pad on the rear driver side brakes was completely out. Almost metal to metal. Strange that the inside pad still had a good 40% left. I was told the outside pad was probably stuck so it would constantly rub against the rotor. Seems like he was correct because there's a big dip where the pad was in contact with the rotor. The rotor is probably ruin but I'll try to see if it can still be turned. If not then I'll replace it with a new one this weekend. I know it's recommended to change the rotors in pairs but would it bad if I just replaced one side because the other side is still fine.