Question: I enjoyed your article "Trailer Wheel Bearing Talk." Could you talk more about tire safety? I look around in parking lots and see many tires that are unsafe. Thanks!

Answer: This is certainly a good topic. Tire talk is an important conversation as their main functions include supporting the vehicle load, transmitting traction and braking forces to the road surface, absorbing road shocks, and changing and maintaining the direction of travel.

To ensure these functions are being adequately met, there are some important things to inspect on each of your vehicle’s tires on a regular basis:

  • Tread depth of your tires
  • The air pressure. Check tire pressure with a tire gauge. Tires can be as much as 50 percent under-inflated before it is visibly noticeable.
  • The wear or any damage or signs of deterioration. Tread or sidewall cracks, cuts or snags deep enough to expose the body cords

Tread depth is essential to a well performing tire. Water accumulates on the road during wet conditions. Tires need tread for better traction during these harsh conditions. The grooves on your tires work to siphon water away from the surface of the tires when the road is wet.

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  • Checking the tire tread depth. Tires with a tread depth of one-sixteenth of an inch or less are unsafe. Place a penny head first into the tread grooves nearest the center of the tire at three locations equally spaced around the circumference of the tire. If you see the top of Lincoln’s head, you need new tires.
  • Tread wear indicators (wear bars) are located at the base of the main grooves and are equally spaced around the tire. The tread wear indicators which look like narrow strips of smooth rubber across the tread, will appear on the tire when the point of wear is reached. When you get to this point, you need new tires.

A portion of state statutes were used with permission from the Office of the Revisor of Statutes. If you have any questions concerning traffic related laws or issues in Minnesota, send your questions to Trp. Jesse Grabow – Minnesota State Patrol at 1000 Highway 10 West, Detroit Lakes, MN 56501-2205. (You can follow him on Twitter @MSPPIO_NW or reach him at, jesse.grabow@state.mn.us).