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TIRE MANAGEMENT: INFLATION

Posted: August 1, 2014

A successful tire strategy — and you need one — is really pretty simple: keep an eye on the pressure inside the tire. The Technology & Maintenance Council of the American Trucking Associations (TMC) recently conducted a study analyzing tire tread collected from 13 stretches of
highway around the U.S. The task force conducting the study found that underinflation was the major cause of premature tire failure, sometimes compounded by undetected cuts, punctures or other road damage.

Unsightly and potentially dangerous, the large chunks of tread from heavy-duty tires at the roadside have elicited more than a few negative comments over the years about “truckers and those cheap retreads they use.”

Retreads are getting more than their share of the blame here, but the result is the same whether it’s a new product or a retread. The fact is, if you under-inflate a tire, it will fail prematurely.

“The proportion of retreads that were judged to have failed prematurely because they were improperly retreaded — bond failure, missed nail holes, tread ‘list’ and the like — was just 8% in the latest study,” explains tire-management consultant and TMC task force chairperson Peggy Fisher. “Evidence of underinflation, on the other hand, was widespread.”

There may be other factors at play as well, such as heavier loads and higher average road speed, but in the end, it all comes back to inflation pressure.

By maintaining proper tire pressure, you limit the amount of flexing that the sidewalls experience as the tire rotates. That flexing generates heat, which is often compounded by the friction-generated heat produced in the tread area. Combined, all that heat can prove fatal to tires in a short period of time.

The Meritor tire inflation system by P.S.I.

We know the cause, and we’d all secretly admit to knowing the solution. But geez, who’s got the time to check all those tire pressures every day?

It’s a valid concern. And as much as any fleet manager might like to hand that responsibility off to the individual at the wheel, it’s really a shared
responsibility. Drivers can have a tremendous impact on tire life, but if the driver isn’t paying for the rubber, where’s the motivation for taking on the responsibility of checking tires? It just isn’t there.

It’s obviously different if you’re an owner-operator with a very direct connection between the rubber and your wallet, but even there it’s tough to stay on top of tire pressures.

So, what’s the answer?

INLATION MONITORING
There are solutions on the market right now that can minimize or even eliminate the driver from the role of ‘tire kicker’. The Cat’s Eye tire-pressure maintenance tool, for example, is nothing more complex than a valve that equalizes pressure between tires in dual sets. But the eye of the valve contains a visual indicator to alert the driver to a decrease in tire pressure.The units are sold precalibrated to certain pressures, so the user can see at a glance if a set of wheels is losing pressure. And it features a central airing point, which greatly minimizes the aggravation of pressuring up those inside duals.

What the driver does with that information is out of the hands of the manufacturer, but at least he’s been made aware of the problem. From Link Manufacturing, the Cat’s Eye is a simple and inexpensive device to aid drivers in monitoring tire pressure, but it won’t play an active role in correcting the problem. This is a passive system.

An active system, on the other hand, will alert the driver to the problem, automatically re-inflate the tire, and record the event in its memory log.

Better still, these systems can be a very real advantage in certain kinds of operations. They were first developed for military use.

With the abandonment of so many spur rail lines over the past decade, grain farmers in Saskatchewan face a real problem, for instance.

Delivering their product to the remaining railheads demands longer trips by truck, but the need to run some of the way on secondary roads means that load weights can’t be high enough to be efficient.

To combat the problem, the Transportation Partnership Policy of the Saskatchewan government helped develop vehicles for grain and other heavy hauls that can be safely accommodated on rural roads. Using an oversized, heavy-load Super B-train that hauls up to 56 metric tons, the
Saskatchewan Wheat Pool is now able to haul the heaviest loads on even the secondary roads.

The secret? Pre-programmed central tire inflation and variable tire pressure technology that lets the driver partially deflate the tires to create a softer ‘footprint’ on the road surface when the load condition or vehicle speed permits it. It’s that softer footprint that ’embraces’ the road surface rather than attacking it as a firm, fully inflated tire would.

But isn’t it bad for the tire to run it under-inflated? Yes, but not if the appropriate vehicle condition (unloaded, and/or modest speed) is in effect. It’s all based on tire deflection: the change in tire cross-section height from its free-standing status at full inflation to the loaded height. You can use half the tire pressure on an empty vehicle that you’d use on a loaded one and not hurt the tire, because you’re still operating with the proper
deflection range for the tire. The same effect applies if you reduce speed. But you can’t run fast and soft. It may be better for the pavement, but it’ll wreck the tires.

See, tire management is easy. You can take an active approach or a passive one, but there’s more than one way to manage tires. It’s an idea worth kicking around.

TIRE CARE FOR THE DRIVER
Owner-operator or company driver, you really can make a difference in the life expectancy of the rubber you’re riding on. Yeah, there’s a little effort required, but nothing good in life comes free.

According to the TMC, of the top five reasons for premature tire failure and increased operating costs, four are easily controlled at the driver level:

1. Proper monitoring and reporting of tire condition during pre-trip inspections.

2. Regular observation of actual cold tire pressure with an accurate pressure gauge.

3. Watch for rocks and nails drilling into the tires. Catch them before they puncture the casing.

4. Stay motivated. Flats mean downtime, and that costs you money too.

What else can drivers do?

* Request an inflation pressure check-up prior to a regular PM inspection so the mechanics won’t forget.

* Pay special attention to trailer tires. The 1998 TMC task force study revealed that 71% of the tread fragments collected had a rib pattern, indicating that they likely came from trailers rather than power units.

* Make the extra effort to check the pressure on the inside dual. If you can’t find the valve stem, report it as an unserviceable tire.

* Request that the fleet install tire-pressure decals for easy reference, or perhaps consider an inflation monitoring system.

* If in doubt, ask the shop to teach you the correct method checking tire pressure.

* Keep track of tire pressures. Truck tires will naturally lose about two pounds of pressure a month just by air permeating the inner liner and going through the tire. Air can also escape between the bead and wheel, as well as through improperly tightened valves, torn rubber valve grommets, or valve cores that have been blocked open by dirt and ice. Then there are nicks and cuts to watch for.

* Remember what a pain in the neck a flat can be. Stay pro-active.

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