How can I tell when my tires are worn so much that they need to be replaced?
That is a very important question. As we discuss the matter, keep in mind that one of the most important jobs of your tire tread is to move water. The channels in the tread act as passages for water to escape from underneath the tire. The deeper the tread, the deeper the channel – and the more water that can be evacuated.
When enough water can’t be moved from underneath the tire, the tire can ride on the water – often called hydroplaning. The tire is literally not contacting the road but rather is “floating” on the water so there is little traction and the vehicle can slide.
So somewhere between a brand-new tire and a bald tire lies the point at which the tire should be replaced. Some governmental jurisdictions have minimum tread depth requirements others do not. So, check the laws where you live to learn the legal minimum.
Tire manufacturers are required to mold a treadwear bar into the tire. This bar appears across the tread when the tire is worn down to 2/32 of an inch. If you were to insert a US penny upside down into the tread on your tire and the tread did not come to Abe Lincoln’s head, your tires are worn below 2/32 of an inch.
Studies have shown, that there is a significant difference in stopping distances in wet conditions with tires that have less wear. For example, in controlled, wet conditions a vehicle with 4/32 of an inch of tread traveling at highway speeds was able to stop in about 85 feet less distance than the same car with tires with 2/32 of an inch of tread. That could easily be the difference between a safe stop and hitting the vehicle in front of you.
You can gauge 4/32 of an inch by inserting a US quarter upside down into the tread. If it covers George Washington’s head, you have more than 4/32 of an inch of tread.
New tires are a big-ticket item so it’s natural to want to get as much value out of them as possible. Just remember that a huge part of that value is the ability to stop safely in wet conditions. Talk with your tire professional for help with tire replacement.