The big players in the tire industry including Michelin, Goodyear and Bridgestone Firestone are producing at maximum capacity, and tires still are in short supply. Booming wars and economies in foreign lands continue to choke the world's supply of tires and other resources. And next year's demand should be just as strong. In response to the demand and rising costs, many manufacturers are boosting prices including Goodyear that announced increases as high as 6% in May.

Murray Arcaro, maintenance supervisor for Georgian Aggregates and Construction in Collingwood, Ontario, says his production costs already have increased by 15% to 20% because of rising tire prices. Also, he says, another 15% increase can be attributed to increased tire wear because the company soon will be misapplying tires to certain machines.

The company has resorted to stockpiling for the work year, buying as tires become available from local dealers. Arcaro anticipates the same scenario next year. For example, his quarry face loader calls for E4 quarry tires, but will be fitted with E3 tires. “It does the job, but the service life is much lower,” Arcaro says. The same scenario is true for the rigid haul trucks. He says E3 tires cost about $800 (Canadian) less, but it averages out with the depleted wear life.

“The days of picking up the phone and getting a tire repair man and having him replace the tire to your specifications are gone,” Arcaro says.

Tim Good, Goodyear manager of global customer accounts for off-road tires, says the company has all of its dealers and OEMs on allocation programs. Goodyear advises what will be available for the year so the dealers can make the appropriate decisions. Good says he has never seen demand this high and expects it to continue into mid-2007.

During Conexpo-Con/Agg, Caterpillar Group President Gerry Shaheen said the time from order to delivery for new equipment was as long as 16 weeks. He said tire availability was a big reason for this wait. Caterpillar Vice President Dan Murphy issued a statement saying the company is “exercising a variety of alternatives, including bias-for radial substitutions, adding new suppliers, adding capacity and considering retreads in some applications.”

This surge in demand doesn't stop with tires. Steel, cement and fuel also are being eaten up by zealous consumption. Aggregates are no different.

The U.S. Geological Survey says 2.86 billion metric tons of aggregates were produced in 2004, a 6.7% increase from 2003. And the upcoming year looks to be just as strong.

Georgian Aggregates and Construction is one of two major quarries serving the greater Toronto area, producing 2.25 million long tons of soft limestone a year. Arcaro says increases in production should call for even more tires. Unfortunately gaining the tires to extract more aggregate is becoming more difficult.

Bridgestone Firestone Senior Field Manager Roger Best says some companies have parked machines for as long as a week while waiting for tires. Mostly it comes down to timing, he says, when the current tires fail before the new can arrive.

This puts the aggregates industry in a precarious situation as it tries to reach its own production goals. And since the problem isn't going away overnight, it may be time for the aggregates industry to adjust its own behavior. Stockpiling tires is one possibility, if that option is available. But a refresher on tire science and maintenance can help maximize wear life.

One of the largest factors impacting tire life is sharp rock fragments on haul roads. Generally, as the material's abrasiveness increases, the wear life of the tire decreases. “(Our limestone) is not abrasive, but no tires are puncture proof when you put them on this stuff,” Arcaro says. The operation's four Cat 769 haul trucks eat a set of tires every 6,000 hours. Face loaders spend a set every 4,000 hours. Arcaro says, although the haul roads and loading areas are cleaned two or three times daily, tires rarely survive the full tread life.

Rock cuts are the number one tire killer, Best says. Decreasing those can greatly lengthen a tire's life because every little hairline cut weakens the resilience of the tread and sidewalls. When a tire meets a rock, it becomes the only contact point between the ground and the weight of the vehicle. Best recommends keeping the roads well graded and free of debris.

The slope of the road should be super-elevated. Best says to compare it to Daytona International Speedway, known for its high-bank (31-degree) turns. For instance, if there is a curve to the right, the left side of the road should be banked higher to remove some of the load from the outside tire. If a road is sloped the opposite way, more scrubbing will occur on one side than the other, and spillage also becomes an issue as the load shifts with the lean of the truck. Super-elevation also allows increased productivity because it allows the vehicle to take turns faster.

Tire and original equipment manufacturers often provide consulting to optimize haul road configuration and operator behavior. Good says a 6% to 8% grade is ideal, and anything more than that causes tires to work harder.

Tire experts advise not to allow production demands to eclipse an operator's tire maintenance. There is a cost-benefit ratio, which is affected by multiple variables, that needs to be analyzed. Perhaps the production demands are costing money by exhausting tire life, or the operator could be handling a face loader too aggressively.

An operator's behavior greatly affects tire life. A good loader operator knows how to manipulate the hydraulics to fill a bucket rather than spinning the tires while trying to lift the whole pile from the bottom. A good haul truck driver knows what speed to maintain based on the structure and curves of the road.

Proper loading is essential. Best says, since there are two tires on the front, 33% of the material should be loaded on the front axle with the remaining 67% on the rear axle for end dumps, Best says. The load also should be centered because a lop-sided load will increase wear on the heavier side. This causes the tires' sidewalls to bulge, increasing both the contact area with the ground and the risk of rock cuts. The added weight also makes tires more susceptible to punctures. An operation that is improperly loading trucks, will likely pay for it in the long run.

The vehicle itself is another determining factor. The more weight and torque a machine touts, the faster its tires wear. Arcaro says the Cat 988G wheel loader is a good example. Compared with the prior series of the loader, Georgian Aggregates has watched tire life drop from 6,000 hours to 4,000 hours. However, Arcaro says, tires are paid for by a boost in production.

Water drastically reduces the life of tires, Arcaro says. It acts as a lubricant, which increases the risk of punctures, and wet tires are more likely to spin and generate heat. Georgian Aggregates routinely tries to build up the roads and to divert water away.

Water also causes the steel cords to rust, which can result in a premature failure, says Michael Ford, Michelin market segment manager. Also, exposed cords act as a wick for additional water absorption. This, in turn, can evolve into a structural and, hence, a safety issue. You never want an “open sore,” Ford says. Any tire with exposed cord should be removed and inspected by an authorized dealer, he says.

With so many variables working against a set of tires, flat-proofing foam is one option to extend tire life. This especially is true in underground applications where it is harder to change tires and get to replacements. However, it is best to keep foam-filled tires operating at speeds under 30 mph. Otherwise, Best says the foam could melt or revert. Also, the foam in some instances can prove more expensive than replacements.

Arcaro says his fleet of large earthmovers operate with the flat-proofing product Tire Life, manufactured by Fuller Brothers. He says it helps seal punctures when they occur. It also helps prevent the five-piece rims from leaking. But he mainly uses it to decrease component wear and rim corrosion. Heat generated by speed is not a variable at Georgian Aggregates. The trucks rarely break 15 mph because the longest haul road is only ¾ of a mile.

Tire Life is a coolant, sealant and antioxidant for rims. The company says it also seals O-rings, bead seats, liner porosity and blistered or cracked inner liners without sealing rim cracks and other injuries that require repair.

Fuller Brothers also says Tire Life reduces operating temperatures by as much as 7.5%. It absorbs BTUs of heat from the interface, transfers heat to cooler and thinner areas on the tire, and increases air chamber humidity so extra psi is generated as heat rises in the air chamber. This reduces sidewall deflection and tread squirm.

Also for earthmover tires operating distances less than one mile, Arnco offers RePneu flat-proofing polyurethane fill. The company says it provides heat resistance and has a softness of 28 durometers. This reduces tire deflection and improves tear strength and compression set. Its companion formula RePneu II has a softness of 30 durometers.

Retreading old tires also can reduce tire costs. Arcaro says they retread wheel loader tires with 25% of tread remaining. Retreads are about half the cost of new tires but have 20% less tire life. If they opt out of retreading, the company will let tires run until only 5% of the tread is left. However, Arcaro says it's unusual for a tire to make it that far without unraveling or being punctured. And if one tire fails, they retread or replace the entire set.

To help prevent tire failures, Arcaro checks the fleets' tire pressure weekly. If there is a strong deviation week to week, there is probably damage that could be corrected before a blowout occurs. Watching pressure deviations helps identify tires with small leaks. Running tires with depleted pressure greatly decreases the tire's life and increases the chances of failures.

Tire pressures, in a perfect world, should be checked as often as possible when 24-hours cold. For companies that never park that long, Goodyear's Good recommends daily hot pressure checks. But a baseline should be established with at least one cold check. He says a 20% increase in pressure on the hot check is common. The key is to watch for major deviations from day to day to identify potential problems. But unlike cold pressure, hot pressures can have spikes because heat creates pressure. He also says never release air from a hot tire because recommended psi is configured to cold tires.

To help ensure accuracy Michelin recommends using two pressure gauges. Also, keeping the valve stems capped will help maintain that pressure. “It is such a simple concept,” Ford says. But at more than half of the audits that he has conducted, he finds vehicles with missing valve caps. The valve cap is the primary air seal on the valve assembly. It also blocks dirt or debris from collecting in the valve, which can cause leaks. Wrenching down valve caps should be avoided, doing so can crush the rubber gasket inside.

Tire dealers stress the importance of selecting the right tire for the given application to maximize wear life. However, “the realities of the market are the realities of the market,” Ford says. And more often, operations are misapplying tires because of availability.

Michelin, which specializes in radial tires and does not sell bias-ply tires for earthmovers, says an L5 (radial) tire-rim-association coding often is a good selection for applications working on sharp rocks. If those are unavailable, even from a competitor, Michelin recommends using an L5 bias-ply tire. The company says never resort to an L3 tire on an L5 application because it will not hold up and can become a safety issue. Also, using an L5 tire on an L3 application would generate excessive heat and provide less traction, which causes the tread to outlive the casting.

Bridgestone Firestone does produce bias-ply tires. Best says 80% of the haulage units are on radial because the cost per ton is generally lower. Radial tires provide a bigger footprint for slower wear. And, with today's technology, repairing a radial tire is just as easy as repairing a bias-ply tire. Also, a radial tire has more load-carrying capacity and more resistance to heat and cutting. This greatly makes up for the added cost for buying radial versus bias-ply tires.

A bias-ply tire is layered with rubber-coated plies composed of textile cords wrapped around bead wires. And the only way to increase the strength is by increasing the plies and bead wires that, in turn, create more heat retention. Radial tires have a single layer of rubber-coated steel cables that arch from one bead to the other to form the tire casing. Strength is increased with additional cables that reduce punctures, tears and flats.

But no matter what you're riding on, some basic maintenance and operating practices will keep you rolling through the tire shortage.

Keeping it Safe

They're big enough to crush a pick-up truck. And under even just a few psi, earthmover tires can become extremely dangerous when mismanaged.

Most tire-related accidents recorded by the Mine Safety and Health Administration occur during tire mounting and demounting. Either the massive tires crush the servicemen or a tire explosion kills or injures workers inside the tire's trajectory or danger zone. Michelin Earthmover Training Director Richard Ameris says the safety zone is the area facing the tread but at a distance.

All tires must be deflated before being mounted or demounted to minimize the risk of an explosion. The bead is the tire's link to all wheel or rim components. If those components are improperly assembled or damaged, the whole unit may come apart with extreme force.

One of the most critical components to the rim assembly is the lock ring, Ameris says. It is the last piece that is put on and is what keeps the tire and the rim components together. If the incorrect ring is used or if it is warped or damaged, the rim components are much more likely to give under pressure. The lock ring should be perfectly round and its gap should be within factory guidelines; if not, it should be discarded. Also, it should be inspected every time that it is removed or installed.

The same is true for rim components including flanges, bead-seat bands and driver keys. They should be kept off of the ground during maintenance. And existing dirt and rust should be removed with a wire brush to allow proper inspection and maintain the units' structural integrity.

The tire is a single piece, a pressure vessel maintained by steel components. So long as those components are in proper order, the tire is ready for service, Ameris says. From a safety perspective, a tire inflated at 15 or 25 psi, if not properly managed, can generate enough force to kill or seriously injure anyone inside the tire's trajectory zone.

To avoid potential injury while mounting or demounting, Ameris recommends creating a barrier on either side of a tire as it is inflated. Safety cages should be used for tires with rim diameters smaller than 24 inches. Tires, which are too large to be moved manually, should be supported by the service truck's boom during mounting. This way if something comes apart, any projectiles would be thrown away from the serviceman and against the crane truck's boom or the vehicle.

The largest threat associated with tires involves mounting and demounting. Often, tires slip from the lifting device, whether held by chains, slings or tire hands. It is critical that no one is under a suspended tire, and the machinery is operated at a distance via remote-control. Remote-controlled operations require proper training. If the tire can rotate at all while pinched by gripping pads, it should be lowered and regripped.

Also, tires should be dry while suspended to decrease the chances of a tire falling. An MSHA investigation recently determined that a wheel loader tire slipped from the lifting pads after it had been soaped up for washing. The victim, who was crushed to death by the fallen tire, also had been working an excess of 13 hours prior to the accident. Ameris says working under any suspended tire puts a person directly in harm's way.

Ameris discourages using bead hooks because they provide only one point of support for the entire tire and can damage the tire's interior. Also these types of hooks often are built in-house, rather than by professional distributors. If servicemen are using chains or straps, the tire should be secured by two sets of loops that create four strands for support. Review the specs of the chains or straps to determine if they are strong enough to lift an earthmover tire and meet local legal requirements.

Another mistake that has cost more than a few lives is welding on or near a wheel while the tire is mounted. This is a recipe for disaster because tires can explode regardless of the psi level. Compressed air contains oxygen, which is a combustible gas, and welding introduces a potential ignition source. Ameris says to never weld on a rim component. That should be done by authorized sources like the wheel's manufacturer. And, the tire must be deflated and removed completely.

One way to minimize the explosion risk is to fill tires with nitrogen rather than air because it is a neutral, noncombustible gas. Although, Ameris says, nitrogen has a cost and air is free.

Another potential ignition source is foreign debris left inside the tire as a result of poor maintenance practices. When that tire goes back into service, the debris can fuel an explosion once it is sparked by any number of heat sources from inside the tire.
— Adam Madison