Final answer:
Each tire on a placarded vehicle must be examined at least once during a period of 12 consecutive months. A placarded vehicle refers to a commercial motor vehicle that carries hazardous materials and requires the display of a hazardous materials placard.
Step-by-step explanation:
Each tire on a placarded vehicle must be examined at least once during a period of 12 consecutive months. A placarded vehicle refers to a commercial motor vehicle that carries hazardous materials and requires the display of a hazardous materials placard. According to the Department of Transportation (DOT) regulations, all tires on placarded vehicles should be inspected regularly to ensure they are in proper working condition, including checking for tread depth, tire pressure, and signs of damage or wear.