What part of Lincoln's profile suggests you need new tires when using a penny to check your tread depth?

If you're using the penny trick to check your tire tread, place the penny upside down into the tread, the top of Lincoln's head first. If some of his head is covered, no need for new tires; but if you see his whole head, you'd better invest in some rubber.

Asked by Tom Cohen · Last updated 4 years ago · 1.4K views · SOURCE