It’s old news that tire pressure monitoring systems (TPMS) are now required on new passenger cars, light trucks, and SUVs with GVW ratings up to 10,000 lbs. However, most regulatory observers agree that the congressional mandate applies to all highway vehicles, and requirements covering commercial trucks through Class 8 are likely within the next several years.
To keep up in today’s market, it is vital to consider new ideas, new technology and different approaches against the background of the changing conditions in which we operate if we want to enhance operating efficiency as a key strategy to ensuring success for the fleet and the dealer.
Not only can implementing a TPMS help in this arena, but the systems can also provide protection from dangerous problems like zipper ruptures.
Think about the thousands of truck tire debris pieces alongside roadways, almost every one responsible for an unscheduled (and expensive) service stop. It has been well documented that many of these failed tires share several common traits they were underinflated and fitted to an inner dual tire position.
Consider that, for every one of these tires, many others continued on without the benefit of proper inflation for the load being carried until the driver noticed a flat or it was found to be inflation-deprived during a routine tire change or PM check.
When steel-ply tires are operated in underinflated/overloaded conditions, the ply cords are deflected beyond their design limits, much like bending a coat hanger or piece of baling wire repeatedly until it breaks. Ultimately, fatigue failure occurs in the upper sidewall area, beginning with the fracture of one or more ply cords, then progressing circumferentially, resembling a “zipper” opening. This often results in immediate, explosive air loss, generating force that can be extremely hazardous even deadly to anyone in the immediate area.
Many of these overworked tires show little or no visual clues of their working history. Innerliners of older bias-ply tires showed discoloration, often accompanied by localized liner distortion, when they were run underinflated. This made visual detection fairly reliable. Not so for today’s tubeless radials.
For years the industry has worked to develop some type of non-destructive, shop-friendly inspection criteria to separate those overworked tires suitable for returning to service from those that should be scrapped. Failure to detect potential “zipper breaks” can result in premature casing failures, road service expenses, retread investment in unworthy casings, and, most serious of all, injury to tire servicing technicians or retread plant workers.
One simple solution to ensuring a fleet is 100% free of zipper ruptures is installing and maintaining a reliable TPMS. With notification of inadequate tire pressure, drivers will be sure to catch any problems before they escalate to emergency levels.
Dealer and retreader personnel are better protected because reliably inflated and maintained tires are less likely to develop potentially catastrophic problems. And, as if the added safety and peace of mind weren’t enough, it also makes sense financially for any fleet to consider TPMS.
Dollars and Sense
While overall highway safety and reduced incidences of unscheduled roadside stops have been driving factors for federal government interests, there’s reasonable expectation that these systems, if properly designed and selected, could change the face of commercial tire maintenance in very positive ways mainly, saving fleets a lot of money.
In passenger cars, the sole focus of TPMS is real-time inflation monitoring, driver notification that is usually in the form of a prominent dashboard display. Since retreading and casing durability beyond original treadlife is of negligible interest to most car operators, inflation history, statistical records, and reviews by tire dealers and maintenance managers aren’t part of the program.
For commercial operations, long-term financial benefits likely to accrue from more consistent and precise inflation maintenance are better treadwear (extended removal mileage), longer casing life (more retreads), and fewer expensive road calls/freight delays. Fuel economy gains will also be likely.
Currently available devices approach the task in a variety of ways, ranging from simple monitoring to automatic inflation replenishing, with a choice of sensing and communication options.
Key questions a fleet should ask when considering TPMS choices are how much detailed information they want to gather, to whom it should be directed, and if the fleet wants the TPMS only to warn of pending problems in real-time or to be an integral part of standard safety and maintenance programs.
Options, Options, Options
The first major distinction to consider lies between systems that monitor inflation and those that also maintain inflation to a specified pressure. The latter types are currently available for trailer, dolly, and other non-driven axles except steer. Air supply is typically plumbed through the hollow axle housing and sourced from a brake supply air reservoir.
There are some externally supplied systems used in parts of Europe and South/Central America that also inflate steer and drive axle tires using tethered hoses and rotating slip-ring pressure seals. However, these are generally not considered practical for North American service conditions narrow toll booths, congested urban delivery sites and width-restricted construction lanes that are not for the faint of heart. Several manufacturers said that more compact systems will soon be introduced for steer and drive axles, allowing total vehicle monitoring and automatic inflation maintenance.
Another distinction is between hard wired communication and wireless transmission of inflation problems. Some early devices simply offered visual displays for tire checks on stopped vehicles, such as during pre-trip and fuel island inspections. Today, continuous real-time monitoring appears to be gaining preference.
Wireless communication is also available from some systems and while most today are stand-alone, it would seem that integration into a vehicle’s basic wiring harness would enhance reliability. Both active (battery required) and passive (true RF technology) devices are being promoted and, although batteries may be undesirable to some, battery life claims of five years or more have become common.
Some fleets may want to have real-time warnings transmitted directly to a home-based logistics center, where en-route service providers can be located immediately and a message can be quickly sent back to the driver, directing them to the service destination.
All of this may sound a bit confusing, but keep in mind that some fleets have already adopted TPMS, most notably for trailers, and most are reporting tremendous reliability. Systems for the entire vehicle won’t be far behind, with a promise to further reduce fleet operating costs.
It’s time to learn more about TPMS and plan to use it to your advantage. If you need some guidance, tire and TPMS engineers can help evaluate and quantify the benefits possible for a fleet’s specific equipment, service conditions and maintenance practices.