Tire tread gives your vehicle traction in both wet and dry conditions. Various factors like temperature, rough surfaces and sometimes harsh drive habits cause tread to wear down over time. Worn tread increases the risks of an unsafe ride and decreased traction. If you start to notice less gripping and increased shaking while braking, check your tires. One of the easiest ways to measure each tire's tread depth is with a penny or quarter.
Penny tread test
Checking tire tread with a penny is one of the oldest and most reliable techniques for measuring tread depth. Insert a penny between your tire's tread blocks with Lincoln's head upside down towards the tire. If Lincoln's head is completely visible, the tread is worn out and your tires should be replaced. However, if part of Lincoln's head is covered, there is more than 2/32 of an inch of tread depth, meaning your tires are typically in good shape. Make sure to check several portions of the tread pattern, including central, outer and inner grooves.
Quarter tread test
Depending on the vehicle or a driver's habits, having 2/32 of an inch of remaining tread might not be enough traction. Some independent tests show that having 4/32 of an inch of tread or more remaining on your tires ensures better traction and braking. If you prefer the added security, use a quarter instead of a penny to test the tread depth. Similar to the penny test, insert the quarter into the tread blocks with Washington's head upside down. If part of Washington's head is covered, there is more than 4/32 of an inch of tread left, which means your tires don't need to be changed.
Tread wear indicator
Most manufacturers have tires with built-intread wear indicators. Tires have a rubber bar that slightly protrudes within the grooves when it's brand new. Each tire is typically equipped with six small tread wear bars. If the bar blends in with the rest of the tread, then your tires should be replaced.