Apple has been dabbling in wearable tech, at least when it comes to the U.S. Patent Office, and a new application uncovered Thursday by AppleInsider adds to that growing category. Apple has filed for a patent covering so-called “smart shoe” systems which feature sensors that can track wear and usage and tell you when you need to replace them, charting your progress on a companion app for a mobile device, or via built-in LED lights, speakers or displays.