So…. you’re starting to notice some wear on your tires and you’re wondering, is it time for new rubber all the way around or can I just keep rolling?
Probably the first thing you need to think about is your tire “tread.” Treads are the deep grooves in the section of the tire that actually hits the road. A tread’s whole function is to give water, mud, snow, etc. a place to go as a tire rolls through the stuff. Without the tread, mud, snow – even water – would literally lift the tire off the road. So those grooves are important because they help the rest of the tire stay in contact with the road. And of course, if your tires stay in contact with the road, your car has a lot better chance of staying on the road, too
So it is tread depth – (the depth of the grooves in the part of the tire that contacts the road) – that will determine whether it’s time for you to invest in a new set of tires.
How do you check tire tread for yourself? Simple. A penny or a quarter will do the trick.
The Penny Test for Tires - How it works
Just take a penny, hold it vertically with Lincoln facing you and place the dated section of the coin into several tread grooves across the tire. If part of our 16th President’s head is always hidden by the tread, you have more than 2/32" of tread depth remaining.
If you duplicate the process with a quarter and part of Washington’s head is always hidden, then you have more than 4/32” of tread depth remaining.
If you repeat the penny measurement -- this time with the Lincoln memorial facing you but upside down – check to see if the top of the building is completely hidden. If so, it means you have more than 3/32” of tread depth remaining.
After you establish a ballpark tread-depth for the first section of your first tire, begin checking tire tread depth on your other tires. To do this, just repeat the process – and be sure to check a couple of different sections of each tire, including the middle grooves. Measure inner and outer grooves, as well. That will tell you whether your tires are wearing evenly.
If the penny test for tires reveals that the treadwear is uneven, but there is still enough depth to avoid replacing the tires, first check the tire pressure. Then think about having the wheels re-balanced or the vehicles “alignment” checked
Additional considerations when checking tire tread