Final answer:
Tires are not considered safe and should not be operated when the tread depth is less than 2/32 of an inch. This is the legal tread depth limit for most states, and driving with tread worn below this limit increases the risk of accidents.
Step-by-step explanation:
The question refers to the minimum tread depth considered safe for tire operation. No tire is in safe operating condition if the tread is worn to less than 2/32 of an inch. This measurement is the legal minimum in most states and provides the necessary traction to stop safely in wet conditions. When the tread is worn down to this point, tires are often referred to as "bald" and can significantly increase the risk of hydroplaning or losing control of the vehicle in adverse conditions.
It is important for drivers to regularly check their tire tread depth to ensure safety on the road. A simple way to measure this is by using the penny test. Insert a penny into the tire's tread groove with Lincoln's head upside down facing you. If you can see all of Lincoln's head, it's time to replace the tire. Remember that properly maintained tires are critical for overall vehicle safety.