Final answer:
To measure tread depth on a tire, use a tread depth gauge on the tread wear indicators or the center rib, ensuring the measurement is above the legal minimum for safety.
Step-by-step explanation:
The question asks how to measure the tread depth on a tire, which is a practical application of physics principles relating to friction and safety in automotive contexts. Tread depth is a measure of the depth of the grooves in the tire's tread, which are critical for providing the necessary traction to maintain control of the vehicle on various surfaces. To measure the tread depth, you can use a tread depth gauge by inserting it into the tread wear indicator or at multiple points along the center rib of the tire. This measurement should be taken in several areas to ensure accuracy, as tires can wear unevenly. The legal minimum tread depth varies by country but typically is around 2/32 of an inch (1.6mm). If the tread depth is below this level, it significantly increases the risk of tire-related accidents due to inadequate traction, particularly on wet or slick surfaces.