Are your tires worn out? What is the standard for our streets?

Are your tires worn out? What is the standard for our IL

streets? How can you tell on your SUV, Truck & Van?

While there may be legal

requirements for our area, there are safety concerns that go beyond meeting

minimum replacement mandates.

2/32 is the depth of the tire tread wear indicator bars that US law

has required to be molded across all tires since August 1, 1968. When tires are

worn so that this bar is visible, there’s just 2/32 of an inch – 1.6

millimeters – of tread left. It’s that level of wear that’s been called into

question recently.

We’re referring to the Consumer Reports call to consider

replacing tires when tread reaches 4/32 of an inch, or 3.2 millimeters. And the

recommendation is backed by some very compelling studies.

The issue is braking on wet surfaces

in and around town. Most of us think of our brakes doing most of the work, but

if you don’t have enough tread on your tires, the brakes can’t do their job.

When it’s wet or snowy, the tread of the tire is even more critical to stopping

power.

Picture this: you’re driving over a water covered stretch of road in town. Your tires must be in contact with the road in order to stop. That means that the tire has to move the water away from the tire so that the tire is actually contacting the road and not floating on a thin film of water.

Floating on the surface of water is

called hydroplaning. So if there’s not enough tread depth on a tire, it can’t move the water out of the way and you start to hydroplane.

In the study a section of a test track was flooded with a thin layer of water. If you laid a dime on the track, the water would be deep enough to surround the coin, but not enough to cover it.

A car and a full-sized pick-up were

brought up to 70 miles per hour, or 112 kilometers an hour and then made a hard

stop in the wet test area. Stopping distance and time were measured for three

different tire depths:

New tire tread depth

4/32 of an inch

2/32 of an inch

So what happened with the 2/32 tires

on the car? Get this – when the car had traveled the distance required to stop

with new tires, it was still going 55 miles an hour. Stopping distance was

nearly doubled to 379 feet and it took 5.9 seconds.

Wow! That means if you barely have

room to stop with new tires, you would hit the car in front of you at 55 miles

an hour with the worn tires.

Now, with the partially worn tires –

at 4/32 of an inch – the car was still going at 45 miles an hour at the point

where new tires brought the car to a halt. It took nearly 100 feet more room to

stop and 1.2 seconds longer. That’s a big improvement. We can see why Consumer Reports and others are calling for a new standard.

Of course, stopping distances were

greater for the heavier pick-up truck.

How do you know when your tires are

at 4/32 of an inch? Easy; 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. With a Canadian quarter, the tread should cover the

numbers in the year stamp.

You may remember doing that with

pennies. A penny gives you 2/32 to Abraham Lincoln’s head. The quarter is

the new recommendation – 4/32.

How do people feel about replacing

their tires earlier? Well, tires are a big ticket item and most people want to

get the most wear out of them that they can. But do you want that much more

risk just running your tires until they are legally worn out?

For us, and we would guess for many,

the answer is “no”.