For the fleet manager of a large collection of varied equipment, each with different tire needs, managing a replacement schedule for tires can be a challenge. With a well-informed and well-defined tire maintenance and replacement strategy in place, however, a fleet manager will be able to save time and money, while decreasing downtime and increasing productivity.
Many believe the first step in creating such a plan is to establish a track record of tire performance. "The first thing you want to do in developing a tire management plan is to establish a baseline of performance, both current and past," says Bill Porterfield, regional off-the-road (OTR) manager for Titan Tire Corporation. "Doing so will help identify problems and their potential causes."
Tire wear assessment
Porterfield recommends that fleet managers engage their local tire dealer to begin the process of identifying current and past trends in tire wear.
"Some of the most common tire problems are uneven wear, damage to the sidewall, separations in the tire, and damage to the beads or lining — each of which is a telltale sign that the tire maintenance regimen could be better managed," says Porterfield.
Inflation pressure is often the culprit. "Separations in the tire are generally a sign that it has been overloaded or underinflated," says Porterfield. "Continuously running a tire that has insufficient air pressure to carry the load can generate enough heat to cause a breakdown between the materials and the adhesions."
Similarly, he explains that running an overloaded or underinflated tire can cause excessive wear to the shoulders, diagonal breaks inside of the tire and increased deflection, which makes the tire more susceptible to cuts in the sidewall. On the other hand, an overinflated tire can lead to impact damage.
"While faults in the tire maintenance regimen can result in shortened tire life, operator use can have an equally profound impact," says Porterfield. "So, after establishing a baseline of tire performance, the next step in identifying problems is to have the dealer out to the jobsite for an operational assessment."
There are a number of different operator tendencies that can negatively affect tire longevity. Porterfield recommends that you record everything from average haul distances, peak speeds and cycle times, to number of shifts, days worked, cycles completed and type of materials being moved. Doing so helps to forecast expected lifespan under ideal conditions, and thus, identify problems.
"No matter which type of machine we're talking about, there are a few generalities we can make when talking about operator use and its effect on tires," says Porterfield. "Things like rapid stops and starts and sharp turns can put unnecessary stress on the casing, leading to premature wear. Excessive speed generates heat, which can degrade the tire. Additionally, it's important to remember that the heavier the load, the more drastic the impact to the tires will be with all three of these operator tendencies."
For fleets that include larger equipment, such as haul trucks, Porterfield stresses the importance of calculating the operators' ton-mile-per-hour (TMPH) ratings, which utilizes a formula to calculate the heat a tire will generate based on the way it is being operated. TMPH is calculated as the average weight of the vehicle multiplied by the average speed of the vehicle.
"Haul truck tires come with a TMPH rating, and exceeding that rating will cause damage to the tire," says Porterfield. "So it's very important... to conduct an operational assessment in order to determine if the fleet's tires have a sufficient TMPH rating or if the operators are putting those tires through too much abuse."
The final step in identifying problems and developing a tire management program is to conduct a site assessment. The condition of the jobsite and assessment of the natural terrain will not only help your dealer recommend the appropriate tire for the application, but also help identify any obstacles that are causing tire damage.