Ask A Trooper

Sgt. Jesse Grabow of the Minnesota State Patrol

Question: Winter is here. Can talk about tire safety and how a person can tell if their tires are still good?
Answer: Winter season is a good time to remind motorists about the importance of installing and maintaining good tires. Tires must be able to carry your vehicle’s weight and grip the surface of the road properly. Inspect tires regularly for cuts, cracks, uneven wear, bald spots, bulges, and punctures. Carry a good spare tire and check its pressure often. Tires do not have as much traction on gravel or dirt roads as they do on concrete or asphalt roads. Tires have been known to lose up to 1 psi (pounds per square inch) every month. Check your tire pressure often and never drive with under-inflated tires.
• The vehicle’s recommended tire pressure is located on a sticker inside the driver’s door of your vehicle or in the owner’s manual.
• Check your tires before you’ve driven or at least three hours after you’ve driven your vehicle.
• Insert a pressure gauge into the valve stem on your tire. The gauge will show a measured psi.
• Compare the measured psi to the psi found on the sticker inside the driver’s door or in the owner’s manual. DO NOT compare to the psi on your tire’s sidewall.
• If the measured psi is above the number, let air out until it matches. If below, add air until it reaches the proper number.
• Check your tires often for wear and damage problems. A tire is illegal if the tread is less than one-sixteenth of an inch deep. An easy way to check for wear is by using the penny test.
• Take a penny and hold Abraham Lincoln’s body between your thumb and forefinger.
• Select a point on your tire where the tread appears the lowest and place Lincoln’s head into one of the grooves.
• If any part of Lincoln’s head is covered by the tread, you’re driving with the legal and safe amount of tread. If your tread gets below that, your vehicle’s ability to grip the road in adverse conditions is greatly reduced.

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).