Check tires with the " Penny Trick"1
A Lincoln penny is the perfect tire gauge. The "penny trick" works because the distance between the rim and Lincoln's head is 1/16 of an inch -- the minimum required tread depth for proper handling.
Pinch a Lincoln-head penny, from the base between your thumb and forefinger, so that the top of Lincoln's head is showing.
Place the top of Lincoln's head into one of the tire tread grooves and measure in the lowest point within the tread.
If any part of Lincoln's head is obscured by the tread, you're all set -- you have a safe amount of tread. However, if you can see above Lincoln's head, then you are ready for a new tire.
