Final answer:
The tire tread is designed to get water and slush out of the way, improving traction and preventing hydroplaning. State inspections often include a tread depth test to ensure that the tires are safe to drive on.
Step-by-step explanation:
The tire tread is designed to get water and slush out of the way, improving traction and preventing hydroplaning. State inspections often include a tread depth test to ensure that the tires are safe to drive on. If the tread cannot cover at least part of Lincoln's head on a penny, it indicates that the tires are worn out and need to be replaced.
The treads of your tires are designed to get water and slush out of your way, so it is critical to have tires that will pass the penny test. If can't cover at least part of Lincoln's head, your tires will not pass the state inspection.