Today, let’s talk about the effect of tire tread depth on braking. When talking about stopping power, most of us drivers tend to focus on our brakes. But our tires are where the rubber meets the road. So having good brakes isn’t enough. Safe drivers need to have tires with enough traction to translate braking power into stopping power.
Let’s focus on stopping in wet conditions. In order for a tire to have good contact with the road, it has to move the water out of the way. If it can’t move the water, the tire will actually ride on top of a thin film of water.
That’s called hydroplaning. If it’s really bad,drivers can actually spin out of control. At best, you won’t stop as fast.
So how does a tire move water? It has channels for water to flow through. Look at your tire and you’ll see channels: channels that run around the tire and channels that flow across the tire. They’re designed to direct water away from the tire so it can contact the road better.
And the deeper the channel, the more water it can move. A brand new tire has very deep channels and can easily move a lot of water. As the tire wears down, the channels become shallower and can move less water. When it wears down enough, it can seriously affect your ability to stop your car on wet roads.
So that’s why it’s so important to replace our tires when they get worn. Consumer Reports and other advocate groups call for a standard of 4/32 of an inch and they have the studies to prove it.
By comparison, you’ve probably seen the wear indicator that’s molded into tires. When tires are worn 2/32 of an inch, the tread wear bar is visible. So the recommended standard has twice the tread depth as a completely worn out tire.
At Deerfield Tire Company, we want our customers to know that the deeper recommended tread depth makes a big difference. Stopping distances are cut dramatically on wet roads. A safe stop from Illinois freeway speeds with 4/32 of an inch of tread would result in a crash with worn out 2/32nd of an inch tires.
There’s an easy way to tell when a tire’s worn to 4/32 of an inch. Just insert a quarter into the tread. Put it in upside down. If the tread doesn’t cover George Washington’s hairline, it’s time to replace your tires.
Many car owners have heard of this technique using a penny and Abe Lincoln’s head. That measure gives you 2/32 of an inch – half the suggested amount. Of course, tires are a big ticket item. Most of us want to get as many miles out of them as we can. But there’s a real safety trade-off. It’s your choice.