Which of the following is a valid reason for a tire failing inspection?

A tire failing inspection due to excessively worn tread indicating less than 2/32 inches is a critical safety concern. The tread depth on a tire plays a crucial role in providing adequate traction, especially in wet conditions. When tread depth falls below 2/32 inches, the tire's ability to channel water away and maintain contact with the road surface diminishes significantly, increasing the risk of hydroplaning and reducing overall control of the vehicle. This safety standard is widely recognized in vehicle inspections to ensure that all vehicles on the road are equipped with tires that can perform effectively in varying driving conditions.

The other situations described do not necessarily lead to failure. Regrooving above the original groove depth can be permissible under certain guidelines, and tires used exclusively for racing may not be subject to standard inspection requirements. Tread wear indicators being visible typically indicate the tire is still within acceptable limits, as these indicators provide a visual cue to the driver about tread wear and replacement needs.