By Tim Coxwell, Fleet Management Division Director at Leon County Sheriff's Office

The U.S. Tire Manufacturers Association, AAA, and the Tire Industry Association all recommend simple and easy to follow prescribed steps for drivers to inspect and maintain their vehicle’s tires. The steps focus on tire pressure, vehicle alignment, tire rotation, and tire tread.

Tire pressure is often misunderstood. Many people believe myths that the correct tire pressure is located on the sidewall of the tire and that more air pressure leads to better wear for the tires and ride comfort for the driver. It is important for all drivers to locate and read the vehicle manufacturers owner’s manual. A vehicle and the vehicle’s performance are literally the result of a math formula. Using tire pressures that are more or less than the manufacturers specification physically change the outcome of vehicle and tire performance, traction, and wear. If you are unable to find the information in the owner’s manual, open the driver side front door and look for a label professionals refer to as a tire placard. See the image below:

Keep an accurate tire pressure gauge in your vehicle glove compartment. Always inflate tires to the COLD tire pressure listed on the placard or label. What does COLD mean to you the driver? The term COLD when referenced with tire pressure is related to early morning ambient temperatures or when the vehicle has not been driven for two or three hours. Remove the valve cap and position the gauge so that the valve stem core is depressed. It is normal to hear momentary air loss when using a tire pressure gauge. Note the reading displayed by the gauge and reference the specification on the tire placard. Adjust pressure as needed until the gauge reading and specification are the same. The industry standard for inspecting tire pressure is once per month. TIA, AAA, and USTMA also recommended to monitor tire pressure before long trips, like summer vacations, or driving a loaded vehicle, like moving kids to and from college, or when towing campers or boats for recreation.

Don’t ignore the TPMS light. When this light comes on do something about it. Your tires are the only safety feature your vehicle has that actually touches the road. Give your tires and their inflation pressure its due respect. A tire can be damaged enough to fail by being underinflated by as little as 20 percent. 20% of a tire specified to have 30 psi is only a drop of 6 psi. It doesn’t seem like much until you experience a tire failure. Because tire failure is a possibility be sure to inspect your spare tire for pressure and wear along with the tools required to install it. Reference the owner’s manual to familiarize yourself with what to do when a tire failure occurs.

While a driver is checking tire pressure they should also take a look at the tires’ physical condition, particularly the tread wear. There is an old time practice that still holds true to this day. Place a penny with Lincoln’s head down in channels around the tire tread. If most of Lincoln’s Head is covered by tread then your tires have plenty of tread remaining. The all of Lincoln’s head is visible plan on replacing your tires soon. If a driver uses a tread depth gauge, tire replacement is required when a tire tread has 2/32nds remaining. When the tire tread is at or below 5/32nds, drivers should begin to plan for tire replacement. It is preferred to replace all four tires at the same time. If a driver only replaces two tires, the new tires should be installed on the rear of the vehicle. It is not uncommon for a set of 4 new Tier 1 tires (Goodyear, Michelin, Bridgestone) to cost $600.00 – $900.00 – $1,200.00.

In addition to inspecting tire tread depth, drivers should look for uneven tread wear, exposed steel belts, nails, screws, cuts, cracking in the sidewall, or outward bubbles or lumps in the tire. See the Images below:

• Nails in the outer shoulder area are not safe for repair, the tire should be replaced.
• Cuts in the sidewall are not safe for vehicle operation.
• Bent wheels could allow air to leak out of the tire and cause a vibration when driving.
• Impact Breaks are caused from the tire impacting an object, curb, or pothole.
• Shoulder Separation is typically a manufacturer defect, causes vibration, and is not safe.
• Separations are caused by defects in manufacturing or improper tire repairs.
• Overinflation causes tires to wear faster in the center, reduces tire traction, and rides rougher.
• Underinflation causes tires to wear faster on the outside shoulders and premature failure.

With tires being so expensive, how do driver’s maximize tire tread life? Rotating tires along with proper inflation, wheel balance, and wheel alignment will maximize a set of tires’ lifetime. Tire rotation intervals are established by the vehicle manufacturer and listed in the vehicle owner’s manual. If no owner’s manual is available, many tire manufacturers suggest rotating tires every 6,000 miles. USTMA suggests rotating tires every 5,00 to 8,000 miles. When rotating tires, be sure that tires with the deepest tread are placed on the rear of the vehicle.

The most complicated part of inspecting tires is alignment wear. Alignments should be performed by a certified professional using the most up to date equipment and processes. Modern alignment machines are computerized, require specialized lifts, and most newer vehicles require a suitable computerized diagnostic tool to complete the alignment procedure. Specifications for alignment angles are narrow in tolerance and require adjustments as small as a few hundredths of one degree. Once alignment wear is established it cannot be undone. It is recommended to have your vehicle aligned as soon tires are replaced. Alignments may exceed specifications from worn suspension and steering components, or impacts from rough transitions like speed bumps, curbs, or pot holes. It is possible to “knock” your vehicle out of alignment during routine driving. Many tire companies offer lifetime alignments for a higher price than a single alignment. See the alignment image below. Areas in red require adjustment. While the image displays front alignment angles, many vehicles require rear adjustments which are required to be completed before the front can be properly adjusted.

New tires should be match mounted to the wheels using a computerized wheel balancer with the capability of measuring wheel and tire runout conditions. This mounting process provides for the best possible ride comfort or tire wear. See the images below:

Be prepared by becoming informed. Awareness is a primary key to safe vehicle operation. Understanding the significant role your vehicle’s tires play in your safety while driving is the first step. Tires with the best tread also perform the best in all road conditions. Knowing how to keep your tires in good condition will keep your vehicle accelerating faster, stopping sooner, and riding smoother.