Idea: Tire wear measurement

A low power, inductor powered, cheap microcontroller embedded in a tire could be used to detect and warn of tire wear. The microcontroller could measure the change in resistance of thin wire molded into the tires surface. When these filaments broke, from being exposed to the roads surface, a tire wear indication could be sent to the driver. When deeper filaments break, a warning indicator could be displayed.

The filaments could be arranged many ways:
  Resistance measurement of bundles,
  individual strands at multple depths,
  bundles at multiple depths.

In all cases, resistance or open/closed type measurements could be made. As filaments broke in the bundles, the resistance would increase. The depth, spread, and number of the bundles or individual filaments could be chosen to give smoother or coarse steps in depth detection.

I assume this was patented a looong time ago.