• Tread Depth: Per Alabama Traffic Code 32. Motor Vehicles and Traffic 32-5-210:No person shall operate any vehicle of a type required to be licensed upon the highways of this state except for those tires on the dead axle of a vehicle with a dead axle when one or more of the tires in use on such vehicle is in unsafe operating condition or has a tread depth less than 2/32 inch or .15875 centimeters measured in any two adjacent tread grooves at three equally spaced intervals around the circumference of the tire;  provided, that such measurements shall not be made at the locations of any tread wear indicator.  A tire shall be considered unsafe if it has any part of the ply or cord exposed, any bump, bulge, or separation, any tread or sidewall cracks, cuts, or snags in excess of one/fourth inch in length and deep enough to expose the body cords.  Tire(s) described above will be identified as “worn out.” A tire with these issues will be replaced.
  • Age: Tires are manufactured by bonding rubber to fabric plies and steel cords. Despite the anti-aging ingredients mixed into the rubber compounds, there is a realization that tires are perishable, as well as a growing awareness that some tires will actually age out before their treads will wear out. “Nothing lasts forever; tires are no exception and only use tires within the following age range.” Typically, most tire manufacturers recommend tire replacements at 5 or 6 years, regardless of tire condition or tread depth.  University replacement is less than six years of the manufactured date.  Tires have a date stamp on the sidewall that indicates the week and year the tire was manufactured.  This stamp will be used to determine the age and timeline for the replacement of your tires and not the purchase date.
  • Vibration: Vibrations are an indicator of various tire problems, from tire balancing to out-of-round issues. One major tire problem that can cause vibration is when the “belts” or inner cords of the tire separate or shift.  Although this is not visible to the naked eye, it becomes abundantly clear when the tire is mounted to a balancing machine.  The driving feel with a separated tire is described as lumpy at low speeds, which becomes a very high-frequency vibration at highway speeds.  A tire with these issues will be replaced.
  • Weathering: Weathering is a major factor for the tires on your vehicle. Automotive Services staff continue to experience a reduction of 1 to 3 PSI per month with tires, depending on the drastic changes in weather and temperatures.  Tires are endlessly exposed to the elements (heat, cold, snow, ice, and water).  Because rubber is a natural material and will break down over time, you need to be aware of the potential signs of weathering. Typical indicators are fine cracks in the sidewall and in between the tread blocks.
  • Low Air Pressure: When a tire has been run with air pressure 20% below the placard pressure for an extended time (inspection of the tire by a qualified person is needed before allowing any tire run this low to continue in use). Automotive Services will determine if the tire needs to be replaced.
  • All Wheel Drive Vehicles (AWD) and 4-Wheel Drive: Automotive Services will follow the vehicle manufacturer’s rules. Tires on these vehicles may need to be changed at a more frequent interval.

Tire Repair

Not all tires can be repaired. Some have special tire repair limits, and others may have suffered damage too extensive to repair. Returning a permanently weakened or incorrectly repaired tire to service could result in tire failure.

Tire Repair Guidelines

  • Repairs are limited to the tread area only. AS will not repair a tire if the injury extends into the shoulder or sidewall area.
  • A tire puncture greater than 1/4 inch will be unable to be repaired.
  • A tire repair can never overlap another tire repair.
  • The final decision to repair a tire or not will be determined by the Director of Automotive.

Tire Replacement

For continued optimized vehicle performance, it is recommended that all tires be replaced at the same time with identical MSPN.  Deeper tread tires on the rear axle provide better handling, wet grip, and evacuate water, thereby helping to avoid oversteer and loss of vehicle stability on wet surfaces.  Deeper tread tires on the front axle can improve wet straight-line braking and stopping distance.  If only two tires are being replaced, tire manufacture recommends they be installed on the rear axle.  Replacing a single tire on a vehicle can have an adverse effect on suspension systems, gear ratios, transmissions, and tire treadwear (including existing and newly replace tires).  If a single tire replacement is unavoidable, it is recommended that the single new tire be paired with the deepest tread tire from the vehicle (including the full-size spare) (only during an emergency).

Reducing Cost

Departments are encouraged to speak to all drivers to reduce the cost of replacing tires on their vehicles.  Best Practices for drivers and the following are the driver’s responsibility:

  • Avoid Aggressive Driving
  • Avoid Spinouts
  • Brake Lock/Skid
  • Hard Cornering
    • Reduce Speeds in parking decks or sharp curves
  • Lose/worn Suspension Components
    • No jumping curbs, driving on uneven ground, off-roading, avoiding potholes
  • Misalignment
    • Drivers should report significant impacts with potholes, curbs, debris, etc. to Automotive Services immediately
    • Drivers should report vibration and vehicle pulling to the left or right to Automotive Services immediately
    • Impacts with objects can damage rims which affect the tire(s) or the safe operating of the vehicle
  • Improper Balance
    • Thrown Wheel Weights
  • Maintain Proper Inflation Pressure
  • Vehicles must be driven to avoid “Rounding” of the tires
    • This happens when a vehicle sits for long periods of time in one spot.
  • Vehicles must not be overloaded. The total weight of the vehicle and weight of cargo must be under the vehicle manufacture specs.

Tire tread life/mileage warranty is stated for some manufacturer’s tires, and most off-road tires are not given a mileage warranty.  Tire mileage warranties range from 20,000 miles to 100,000 miles.  Unfortunately, due to the variety of road conditions across the country, not all consumers will receive the warranted tire mileage.  These warranties may or may not be extended to Commercial or Government Fleet.  Automotive Services and Fleet Management will work with Vehicle and Tire Manufactures to assist with concerns with tires and how it will advance the safe operation of our fleet.

NOTE: The Director of Automotive Services, Fleet Analyst, and/or the Executive Director of Fleet Management has the discretion to approve or deny any repairs.  This includes tire replacement based on an unsafe operating condition.