As tires wear, tread depth can decrease to the point where it appears almost "slick" with no tread pattern showing. But when is the proper time to replace your tires? While most of us believe using a penny is the proper way to gauge our tire's tread depth, read "When Should I Replace My Tires?" to learn what Honest Abe may not be telling today's drivers.
As a reference, most passenger car tires are molded to 10/32", and some specialty truck tires can be molded to as much as 16/32" tread depth or more. If measuring tire tread depth with a coin, here are some basic rules to remember as tires wear to the critical final few 32nds of an inch of their remaining tread depth.
At 6/32" of remaining tread depth, we expect snow traction to be affected, while drivers will notice a difference compared to when their tires were new. By using a penny, you have more than 6/32" of tread depth remaining if the top of the Lincoln Memorial is covered. If you measure more than 6/32", you are safe to start winter driving, as you have enough tread depth to handle light accumulations of snow. If not, consider replacing your set as snow will affect your vehicle's safety.
At 4/32" of remaining tread depth, we expect snow traction to be limited, while wet traction will start to be noticeably less than compared to a new tire. Since water can't be compressed like light snow, you need enough tread depth to allow rain to escape through the tire's grooves. If the water can't escape fast enough, your vehicle's tires will be forced to hydroplane (float) on top of the water, causing loss of traction. By using a quarter, if Washington's head is completely visible your tire is at 4/32" or below. While 4/32" tires provide better balance of value vs. wet traction compared to 2/32" tires, it may be best to replace your tires if wet traction is your primary concern.
At 2/32" of remaining tread depth, the tire is legally worn out in most states and are in need of immediate replacement. The good news is that you received all of the legal value out of your set of tires. Watch "What Honest Abe Doesn't Tell You About Minimum Tread Depths" to see how stopping distances are greatly affected by tires that have only 2/32" of remaining tread depth. By placing a penny into multiple tread grooves of the tire, if part of Lincoln's head is not covered, the tire has less than 2/32" of tread depth remaining.
If you are looking to replace your tires, shop by vehicle to find the tires that work best for your vehicle.