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Managing tires: the 5,000-foot approach

Posted: April 16, 2015 by Jim Park

TORONTO — How you manage your tire program isn’t as important as what you get out of the management exercise. Really sophisticated management tools and practices will produce tons of information. The big question is, “How valuable’s that data?”

You’ve heard the expression, drinking from a fire hose; that’s what happens when you micro-manage a tire program.

Don’t spend more time and energy tracking your tires than the return you see from the process.

“The only group that I know of that really tracks tires well are the leasing companies; they track tires by vehicle,” notes Darry Stuart, president of DWS Fleet Management Service, and a self-described rebel when it comes to some maintenance practices – tires being one of them.

Big leasing companies can tell you to the 32nd of an inch when a steer or drive will be due for replacement. They can tell you to the fraction of cent what a tire’s lifetime cost will be.

On the other hand, Todd Cotier, director of maintenance at Hartt Transportation in Bangor, ME, has had success with tire program that might be described as the 5,000-foot approach. He watches his tires closely, but not daily.

He has been running the same two brands of single wide tires since 2005, and the mileage he sees from those tires is pretty predictable. Any significant variation from that number gets his attention.

“We expect to get 230,000 miles from the low-rolling-resistance wide-base tires before we pull them from drive axles at 6/32nds” he says.

“After that we put them on the trailer and I stop tracking them.”  It’s just not worth the trouble.

“We don’t run hubodometers on our trailers and we’ve got three-and-a-half trailers for every power unit,” he says. “It would be too complex to track them beyond that point, and it’s hardly worth the effort.”

While that management approach would not fly with giant leasing outfits, it’s just fine with Stuart. 

Stuart is of two minds on that depth of tire tracking. At one end of the spectrum, for fleets that have the wherewithal to pull it off, tire accounting can produce a very robust cost model. But it seldom gets past stage one because of the complexity.

“Generally speaking, most fleets manage tires by what I call general-ledger accounting,” he says. “They take total tire cost and then divide it by the miles traveled – either book miles, satellite, miles or whatever measurement they use. The average, and even above-average fleet doesn’t measure tires very well, because the majority of them will charge the tire going on, but they won’t credit the tire coming off if it has any value.”

He cites an example where a fleet put three sets of tires on a steer axle over a short time because a driver was complaining about them. The fleet will charge a thousand dollars each time to install the tires, but never credit the tire coming off even though it’s only partially worn.

For example, three brand-new steer tires go on with 23/32 of tread. They come off three weeks later with 22/32.

If those tires are moved to another position or another tractor, there’s a good chance it will go on at no cost because the tire can’t be charged twice,” Stuart says. “It’s an accounting problem, but it costs the fleet the ability to track the tires by vehicle.”

He says fleets using general-ledger accounting are missing opportunities. With this approach, the tire’s second or third life often goes unaccounted for. If the tire is moved to a trailer, and the fleet has a 3:1 or 4:1 trailer to tractor ratio, there’s a lot of 32nds of rubber that are never accounted for. If that’s the case in your fleet, you probably don’t have a really good handle on your tire costs.

“I charge them going on by 32nd, and credit them coming off by 32nd. It’s cumbersome, but the vehicle costs can be tracked much more closely,” he says.

According to Stuart, the best method for a smaller fleet to manage tires is to treat each one of them as an asset. You have to study each tire that comes off a vehicle.

“Tires talk,” he notes. “They do it in sign language, but analysis can help determine what, if anything cut its life short, or why it ran out to 400,000 miles. Getting right down to basics, if you keep the right amount of air in a tire and you run it straight, you’ll get the best possible value out of the tire, provided you paid the right price for the tire in the first place.”

Whether you micro- or macro-manage your tires, you’ll still see value in a management program. All you really need to do is keep a close eye on the tires, and that sometimes seems to be the biggest hurdle to successful tire management.

Drive axle Inflation systems

Drive-axle inflation systems might not be the Holy Grail of truck maintenance, but they are in a position to cure a vexing problem. There’s no debating the savings from properly inflated tires.

Inflation systems for trailers have proven their value in the market, but such systems for steer and drive axles have proven elusive. The problem with a steer axle is the solid spindle, compared to the tube-type axle used on a trailer. It’s easier to route the airline through the tube to the spindle and on into the wheel hub with a rotary union and a stator than to work around a solid spindle. In drive axles, the natural barrier is the axle shaft itself.

Obviously eliminating the need for pressure check at all wheel positions will reduce maintenance costs, while at the same time improving tire life and fuel economy.

Currently four suppliers are in the later stages of development of inflation systems for tractors: Airgo, Aperia, Dana and Meritor (PSI). Meritor declined to be interviewed for this story, but the others have offered hints at what’s soon to come, or is already on the market.

Tony Ingram, president and CEO of Oklahoma-based Airgo Systems, told us his company will have a system on the market “in the next few months.”

“We’re still a few months away from commercialization,” he says. “But we have been working with test fleets and OEs to prove and approve the product and we’re nearly there.’

All the moving parts and connections are inside the axle housing, with hoses leading from the face of the hub to the individual wheels. Each wheel has a check valve to prevent both tires from deflating in the event one tire blows out.

“Our focus is to work with the OEs and get the system installed at the factory,” Ingram says. “Retrofitting is more work and would require some special tooling, so we don’t expect to see a lot of activity on that front.”

Ingram says Airgo’s control system will also be able to sense vehicle load through suspension pressure and will be able to inflate and deflate tires to the optimum pressure for the load, which could be a feature well received by fleets that run a lot of empty miles or with declining loads.

The Halo tire inflator from Aperia Technologies is more of a pressure-maintenance system than an inflation system, though it can do that too. The bolt-on Halo uses a small internal pump driven by the rotation of the wheel. Because of its relatively small size, it delivers a fairly low volume of air, but certainly enough to replenish or adjust pressure loss resulting from minor leaks, leaky valve stems, seepage and even temperature compensation.

Reports we have seen show fleets that have tried and tested it are happy with its performance, and say that it does what it’s designed to do. The Halo requires no maintenance, and installs in less than five minutes with common shop tools. It’s reusable and can be used at all wheel positions except the steer axle at this point.

The Halo device is NOT recommended for use on wheels with convex shape such as steer positions.

Dana has been building central tire-inflation systems for military and some vocational applications since the 1980s. These are traction-enhancing systems, which can adjust tire pressure up or down depending on the need for traction in soft or sandy soils. These systems are generally more than is needed in an on-highway application where only top-up air may be necessary to maintain a preset inflation pressure.

However, Dana has a system in development (as yet unnamed) that leverages the sealing technology used on the military side for an on-highway application.

“We’re looking at a sealing technology that’s integral with the axles,” says Tom Bosler, global director, Product Planning at Dana Holding Corporation. “And not just drive axles but steer axles as well.”

The system is based upon technology used in the military CTIS system, but scaled down to make it palatable to price-conscious fleets.

The current version of the product is inflate only, Bosler told us, but added that Dana is working on something that will compensate upwards and downwards.

“It won’t be an adjustable system like the military or vocation designs, but it will be capable of temperature compensation,” he says.

Bosler, like Ingram, offered little detail on the inner machinations of the seals and the air-line routing, except to say Dana has incorporated a way to put air into tires through the axle without external hoses or by pressurizing axles. He did offer that the steer-axle system will use a rotary joint with a cross-drilled spindle.

Dana’s system will be an OE-only offering, with a price point based on total cost of ownership and set by the OEM. There are no plans for an aftermarket installation, Bosler says. Dana has not yet announced an actual launch date.

We are aware, as well, that Pressure Systems International, manufacturers of the Meritor Tire Inflation System are also working on such as system, but that’s about all we know at this point.

There are externally mounted drive and steer axle system on the market, but they haven’t gained wide acceptance in North America as they have in parts of Europe and South America. Ingram says fleets are a bit leery of the external plumbing becoming tangled in road debris or worse, getting broken off.

If maintaining drive-axle inflation pressure has been keeping you awake at night, you may soon be able to get a good night’s sleep. 

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