The rolling rubber that meets the road tends to represent one of the highest operating costs for any fleet. From the moment a new tire is introduced, it is only a matter of time before it scrubs away.
Surprisingly, fleets often fail to give their tires much respect. Tire maintenance is often treated like an entry-level job, and many drivers openly measure inflation levels with nothing more than a smack to the sidewalls. Piles of scrap tires are also filled with examples of irregular tread wear and casings that are too damaged to support retreading.
In contrast, a well-planned tire strategy can have a dramatic impact on the overall cost of these rolling investments.
As obvious as it may sound, the strategy will always hinge on buying the right tire for the right application, and that can appear to be a bigger challenge when budgets are restricted.
Purchasers focus more on the initial price in the midst of tough economic times, admits Steve Haugan, fleet sales manager for Bridgestone-Bandag Tire Solutions. The problem is that these decisions can also lead to higher costs over the life of the tire. Fuel economy can be reduced, retreading opportunities can be limited, and downtime can increase because of outright failures.
Major manufacturers all agree that tire-related data must be collected and analyzed -by fleets and their suppliers -to have a true understanding of tire investments.
“If you don’t know what the cost per mile is or your fuel economy benefit is, or don’t have any idea how many retreads you’re getting, it’s hard to jump to a different brand and decide if you’re doing better or worse,” says Guy Walenga, Bridgestone’s director for engineering, commercial products and technologies.
Fleets appear to be divided on the amount of information that needs to be tracked. A simple costjanuary/ per-mile calculation will involve the initial purchase price of tires and retreading, compared to the overall distance that the tires travel. But Walenga has even seen operations that incorporate maintenance costs ranging from shop rags to road calls.
“If you have warranty issues, and the manufacturer is not dealing with you very adequately or [not] taking care of those problems, that is a cost. You may be throwing away casings the other manufacturers might see as a warrantable item,” adds Goodyear commercial tire spokesman Tim Miller. “You want your supplier to be able to directly or indirectly offer quick turnaround on any warrantable items.”
Still, it is also important to ensure that managers are not consumed by the data collection process.
“Decide what you’re going to follow and when you’re going to review it,” Walenga says. “You could become buried with the data and you might lose sight of where you intended to go in the first place.”
Usually, trends can be identified by analyzing the data on a quarterly basis.
Any successful tire program will also watch for the issues that, left unchecked, can lead to premature wear or expensive roadside failures.
Optimal inflation pressures, for example, need to be established using a combination of weights and inflation tables, while these pressures also need to be monitored on a regular basis to ensure that they are always within 5% of the target.
About 2 to 3 psi will be lost each month as air migrates through the tire and around the bead. That means the tire could lose 10% of its air in as little as three months – an amount that can affect everything from the fuel mileage to the life of the tire itself.
The question, then, is how often someone actually needs to use a calibrated tire gauge. The Tire Retread Information Bureau has for years been stressing “Don’t thump ’em. Pump ’em,” but drivers are still seen whacking the sidewalls and listening for the dull thud that indicates a severely underinflated tire. The action hardly identifies the subtle differences that can still lead to premature tire wear.
“Weekly is good. Monthly is probably adequate and probably more practical,” Miller says, referring to how often long-haul tires should be checked with an air gauge.
Fleet managers are often surprised at the differences that exist. One operation found that a mere 42% of its tires were within a target inflation range of 96 to 119 psi, he adds.
Michelin segment manager John Overing suggests that tire inspections should cover the “Critical 6.”
Low pressures will emerge on a tread in the form of rapidly wearing shoulders as well as the flexing sidewalls that can shorten the life of a casing. In contrast, high pressures will lead to rapid wear in the centre of the tread, introducing the threat of more impact-related damage. (It is an important observation for fleets that have been over-inflating tires in a bid to improve fuel economy.)
Valve caps are often removed from the outside tires on dual assemblies because they are harder to reach, but that sacrifices an important secondary seal for the air, Overing adds, referring to the third issue that needs to be rectified.
Dual assemblies should also be matched in terms of pressures and actual heights. A difference of 3/32 inch in tread depth is no more than the height of a dime stacked on a nickel, but the impact over 100,000 km is the same as dragging the lower tire more than 300 km, he observes.
Irregular wear can also identify mechanical issues that are to blame for premature tire wear. Cupping, for example, could be linked to a broken shock. If one steer tire shows signs of a toe in and the other steer tire shows signs of a toe out, the drive axles are not perfectly parallel.
Walenga says that vehicle alignment should actually be checked every six months – before signs of irregular wear even have a chance to emerge.
Even the mounting procedures need to be inspected. “Once it’s set on the wheel and bolted to the truck, even if there is an issue with vibration or pulling, it’s a long time before someone addresses it,” Walenga adds. In contrast, installers can take a quick look at the GG ring (the raised ring of rubber that is found just above the bead) to ensure that it is an equal distance from the rim flange at every point. If any differences exist, the installer will still have easy access to the tools that can break down the wheel and re-seat the tire.
“You really get costs driven down when you develop an enthusiasm around these things,” he suggests.
Indeed, these steps can all help to extend the life of the tires and protect the casings to maximize the retreading opportunities.
“With 99% of the fleets out there, there is an opportunity to save costs by introducing retreading,” says Haugan. “There are some applications where you can get six, seven retreads.”
To maximize the number of retreads, he also stresses the importance of removing tires before the treads wear down too far. Otherwise, puncture resistance might be sacrificed. Steer tires should be pulled once treads reach 5/32 inch, while drive and trailer tires should not wear down below 4/32 inch.
These final tread depths will still depend on the specific application, however. Haugan knows of one fleet that needed to remove tires with 8/32 treads because of the damage that could be inflicted by scorio-covered roads.
Piles of scrap tires should also be carefully analyzed to identify the reason that casings could not be reused, whether they show snags or cuts in the sidewall, or patch jobs that did not incorporate an appropriate plug. Some of the tires may even be reclaimed in the process. “We can repair a lot of injuries with the crown and sidewall that a lot of people will tend to throw to the side,” says Haugan.
And any decision to switch between different models or brands of tires should also be based on a fair evaluation, with the different options mounted on similar vehicles that travel similar routes. “Concrete is far more abrasive than asphalt,” Overing observes, referring to the impact of one factor that can affect the tests.
A realistic comparison between two brands should also include about six trucks, he adds. “If you see a positive result on one brand over another, you will expand it a little more to see if the results are consistent.”
“Fleets today also need to consider tires as a key component of their fuel savings strategy, and that is something that fleets are not used to,” Overing says. “Different tires have different rolling resistances, and rolling resistance is key.” But this also needs to be compared over the entire life of a tire. “The day before you take it off, it’s at its most fuel-efficient,” he adds.
It is just another way that a proper tire strategy can help to reduce operating costs.