For any fleet, tires are one of the top expenses and a “Safety Critical” component.
Let’s start with SAFETY, since it’s the most important. When a driver depresses the brake pedal, that braking action stops the wheel from turning. It is the tire’s contact patch that grips the road and that actually stops the vehicle. Selection of the tire tread design for the application is key to ensure safety. Today’s tires are better than ever utilizing rubber compounds, materials and enhanced tread configurations that provide excellent dry, wet and snow traction.
Optimizing Costs & Expenses
Minimizing COSTS is also important to your fleet – responsibly saving money allows you to procure the quality materials and supplies to keep your fleet moving. An obvious cost savings with tires is improving ‘treadlife’. Less expensive should not be confused with better value. It’s more important to focus on the expected “cost per mile” of your tires (Fuel and Mileage Calculator). Tires can also impact fuel consumption: Rolling resistance is the energy a tire consumes while rolling under load. The lower the rolling resistance, the less fuel consumed (Rolling Resistance Comparison Tool).
For both SAFETY and COST, finding the best tire for your application is key. Equally important is developing and maintaining a Tire Maintenance Program across your fleet, so that you can optimize the Total Cost of Ownership of your tires, and thus maximizing the return on your investment in tires. A Tire Maintenance Program will help you and your fleet maintain safety, extend the tread life of your tires, and reduce fuel costs.
Getting Started with a Tire Maintenance Program: The Critical Six
Maintaining proper tire air pressure is probably the single most important maintenance activity that a fleet can do to maximize its investment in tires. Driving on tires that do not have proper inflation can be dangerous and can cause tire damage.
To ensure safety and efficiency, fleets should consider the following six major areas when optimizing tire maintenance.
1. Low inflation pressure
Under-inflation is the biggest issue in the commercial vehicle industry. It is the number one cause of premature tire removal. With the advancement in today’s radial casing, it is virtually impossible to determine if a tire is properly inflated without using a pressure gauge. Periodically calibrate the gauges using a master gauge. Over time, usage conditions can cause a pressure gauge to lose accuracy beyond the 2-psi manufacturer’s tolerance range. The time and effort required to verify gauges and to check tire pressure is time well spent.
Effect: An inflation pressure mismatch of greater than 5 psi will result in the two tires of a dual assembly being significantly different in circumference, resulting in irregular wear. This mismatch can also lead to eventual tire loss due to premature casing fatigue. A difference of 5 psi between steer tires will cause the vehicle to pull to the side with the lower pressure. Additionally, under-inflation results in internal tire heat buildup and potential premature tire failure.
2. High inflation pressure
Over-inflated tires increase the likelihood of crown cuts, impact breaks, punctures and shock damage resulting from the decrease of sidewall flexing and an increase in firmness of the tread surface.
Effect: Over-inflation can increase the probability of potential casing damage. This change in contact patch footprint could result in a reduction of traction and tread life.
Maintain all tires at the fleet target inflation pressure based on the tire manufacturer's application data book for the particular axle load (Load Inflation Table Standards).
For passenger and light truck tires use the inflation placard located on the vehicle door.
When in doubt contact the tire manufacturer for assistance in determining pressure.
3. Missing valve caps
Missing valve caps are a primary source of low inflation pressure. Valve caps are used to keep debris out of the core and act as a secondary air seal if the valve core happens to leak. Verify there is a tight seal by using a spray-type leak detector. A good metal cap with a rubber seal will hold tire pressure without a valve core.
Effect: The number one cause of tire pressure loss can be attributed to missing valve caps. Operating without valve caps can result in under-inflation and the conditions mentioned above.
Goal: Install suitable valve caps on all wheel positions. Consider the use of inflate-through valve caps for easier pressure maintenance.
4. Dual mismatch inflation pressure
Dual mismatched pressures can cause a permanent irregular wear patterns to develop. Within a few weeks, this irregular wear can potentially be a cause of early tire removal. Dual mismatched pressure will also impact the matched tire, causing accelerated tread wear and casing fatigue.
Effect: This irregular wear can result in early removal or require tire rotation to minimize the effect.
Goal: Maintain all tires at the fleet target inflation pressure based on the manufacturer's application data book for the particular-axle load. Well-maintained fleets keep the tires within 5 psi of this setting when monitoring inflation pressure.
5. Dual mismatch height
Dual mismatch tread depths (tire height differences) will cause irregular wear. Additionally, the larger tire (the one with the greatest tread depth) will become over-fatigued due to bearing more weight. This accelerates premature casing failure.
Effect: Dual mismatch tread depths can cause a permanent irregular wear pattern in a few weeks, resulting in early removal or a lost casing.
Goal: Match tires in dual assembly with equal tread depths. Well maintained fleets use +/- 4/32" of tread depth as the maximum allowable difference in overall height between the duals.
6. Irregular wear
Proper inflation pressure, correct toe settings and proper alignment can prevent most irregular wear. Steer, drive and trailer axle alignment verification and correction can be performed with a minimal cost or investment in equipment.
Effect: Once a wear pattern develops, it will continue until the tire is rotated or removed to be retreaded or scrapped. Diagnosis and correction of the cause is part of the solution in preventing future conditions. Average occurrence of irregular wear typically results in a loss of tread life, resulting in a much higher total cost of ownership.
Goal: Reduce irregular wear by following proactive tire and vehicle maintenance programs.
For any fleet manager, time is a valuable asset. Investing time in selecting the right tires for the application as well as properly maintaining the tires can deliver a big return. These two actions can directly improve the SAFETY and EXPENSES for your fleet by extending the life of the tires and reducing the overall fleet cost. Many fleets are able to manage an effective Tire Maintenance Program using internal resources, while others are increasingly outsourcing their program. Some tire manufacturers and dealers are now able to offer tire program solutions that help address tire issues before they lead to downtime, low mileage, high fuel cost and safety risks.