Ask a Trooper

[Lee Borgersen]

Ask a Trooper: How do you determine if your tires are unsafe?

 Dec 6, 2015
 
Q: How do you determine if your tires are unsafe?

A: Tire talk is important for any time of the year. But now as we get into the winter and snow season, it’s an important time to double your efforts when maintaining your tires.

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Over the years, I have investigated numerous crashes where worn tires were a contributing factor. Tires with inadequate tread depth can cause your vehicle to skid or slide out of control on a slippery or wet road surface. When losing control of your vehicle, you can easily go off the road and into the ditch, or into oncoming traffic, possibly causing a serious injury or death to all involved.

According to Minnesota State Statute 169.723 a tire shall be considered unsafe if it has:

Any part of the ply or cord exposed; or
Any bump, bulge or separation; or
A tread design depth of less than one-sixteenth of an inch measured in the tread groove nearest the center of the tire at three locations equally spaced around the circumference of the tire, exclusive of tie bars or for those tires with tread-wear indicators; or
Been worn to the level of the tread wear indicators in any two tread grooves at three locations; or
A marking "not for highway use" or "for racing purposes only" or "unsafe for highway use"; or
Tread or sidewall cracks, cuts or snags deep enough to expose the body cords.
My best advice is to keep a regular eye on your tires. Check the tire pressure often. A tire can be as much as 50 percent underinflated before it is visibly noticeable. Take a pressure gauge to each tire and know what your tire pressure should be at. Routine maintenance is good insurance. Rotate and balance according to your vehicle owner’s manual. Alignments also are important. Some signs that you might need an alignment:

Your car pulls or drifts away from a straight line.
Rapid or uneven tire wear. 
The spokes of your steering wheel are off to one side while driving on a straight and level road.
Taking a few seconds to walk around your vehicle before leaving for your destination can pay off in a big way, potentially keeping you from getting into a crash. Speaking from personal and professional experience, the “snow” tires I run at this time of the year have made all the difference in my traveling throughout some of the deepest snow and treacherous conditions. I would not want to be without them. Having a set of tires with good, legal tread depth will increase your chances of not being involved in a crash, especially when the weather and road conditions become poor.