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Special Report: Tire trouble
Posted By Equipment World Staff On June 12, 2007 @ 2:10 pm In In the Magazine | No Comments
China’s explosive growth, the war in Iraq, a shortage of raw materials and the boom in mining and construction all came together in late 2004 to create a huge spike in demand for earthmover tires.
How tight is the market? If you attended the ConExpo-Con/Agg construction equipment trade show in March you were no doubt impressed by all the machinery on display. What you probably didn’t realize is many of the big machines were shipped to the show barefoot – that is, without tires – and that many of the tires put on them were leased or borrowed just for the show.
“We have high demand in nearly all dimensions – from the 15-inch to the 63-inch, the largest tire we make,” says John Funke, Michelin’s director of marketing for earthmoving tires in North America. Michelin has a new plant planned for Brazil that will be complete in 2007 and, like most other manufacturers, has increased capacity at its existing factories.
“We’re bringing on additional people, working over weekends, and ramped up to absolute full capacity,” says Cara Junkins, manager of off-the-road field engineering for Continental Tire. “But by the time you get a new tire build machine up and running, you’re talking up to 18 months. Plants can take even longer than that – two years or more for an off-the-road tire plant.”
Although nobody is making firm predictions, most feel the tire shortage will continue well into 2007.
So what’s a contractor to do? If you’re not already, you need to get serious about your tire maintenance and planning. Start doing today everything you can to maximize the life of the tires you have. If you don’t, you may find yourself parking otherwise healthy machines, all for a lack of adequate tires. Unlike classic supply-and-demand situations in which the highest bidder wins, price has not trumped fairness in this shortage. To keep one customer from taking advantage over another, tire manufacturers are maintaining the same percentages they sell to each OEM and end user, in effect spreading the pain around equally. It doesn’t matter how much you’re willing to pay – you can’t buy your way out of this problem. You have to manage it.
For some executives and top managers in big construction companies, tires may have been just another line item in the budget. “Now tires are suddenly at the top of the list in management meetings,” Funke says. And these owners and managers are asking the tire industry to help them out. “There are a lot of best practices and expertise available,” Funke says. “Everyone’s sharing information now to help the whole industry get through this critical period.”
One of the best ways to get a picture of what your tire replacement needs will be in the future is to use tire-tracking and asset-management software.
There are differences between the programs offered by manufacturers, but they all do several things in common including:
· Track every tire in your fleet, regardless of brand, from the time it arrives through recapping and repairs and finally disposal
· Evaluate tires on a cost per hour or any other metric you need
· Compare the durability and suitability of different types of tires
· Gauge whether a particular brand of equipment or a particular site or operator is harder on tires
· Tell you if a particular tire is consistently losing air pressure and needs attention
· Tell you when to rotate or retread tires
· Predict your future tire needs six months or even a year into the future, enabling you to place orders well in advance
Mining companies have used this kind of software for years, but the average construction contractor or quarry typically doesn’t have the manpower to crunch these numbers. “Tracking programs take a lot of time,” says Tim Good, manager of global customer accounts, off-road tires for Goodyear. “If you rotate a tire, you have to note that. If you change a tire you have to note that. Some customers do it themselves, but the dealers can do it for you too, as a value-added service.”
“If I were a quarry manager, I would rely on my tire provider to provide the software support,” says Shawn Rasey, director of corporate accounts for Bridgestone Firestone off-road tires. “Just outsource it. That’s what tire dealers do for a living.”
Rasey compares tire tracking software to engine oil analysis in that both allow for predictive maintenance and reduce the likelihood of surprises and catastrophic failures. “Once you’ve established a metric, you can tell if things are getting better or worse.” Visual inspections, says Rasey, only tell you what your needs are today. The software can tell you what you’ll need well before your current tires wear out. Working closer with your dealer on these future needs also helps the dealer forecast better, which can alleviate some of the bottlenecks and spot shortages in the distribution system.
Having software alone, however, is not a panacea, cautions Funke. “You also need a very aggressive top-to-bottom tire optimization plan everyone embraces and that provokes behavioral changes at all levels of the company. Everyone must support efforts to extract the full value from every tire you have,” he says.
Best practices: now more than ever
Most proactive equipment fleet managers have a strategy to control tire costs and minimize downtime. In the face of today’s shortages, however, everyone needs to rigorously adhere to a thorough best practices program.
As boring as it may sound, there is nothing more important to a good tire maintenance program than checking and maintaining the correct air pressure. While an under-inflated tire on a pickup truck or passenger car may cause uneven wear or handling problems, on a 40-ton truck it can be a recipe for disaster. In a worst-case scenario, under-inflated haul truck tires have been known to heat up to the point of catching fire. And once tires catch fire, the only way to put them out is to bury them – bad news if it’s attached to a million-dollar-plus truck.
Even if you don’t set your tires on fire, underinflated and overheated tires live a much shorter life than their well-cared-for brethren. Checking air pressure on a regular basis is good, but you have to maintain the proper air pressure as well, and that requires you to pay attention to tires with chronic problems and fix them immediately. Even a little bit of overheating, if left untended, reduces tire life.
“If a tire needs air every day, I liken it to an engine that needs a quart of oil every day,” Rasey says. “You probably have a bigger problem that needs to be addressed.”
By changing to a proactive air-pressure maintenance program, Rasey says contractors who have neglected this in the past may see as much as a 10 to 15 percent increase in tire life, as well as additional benefits. “When your air pressure is right, you have the optimal tire shape, which gives you optimal braking, cornering and fuel efficiency. It allows your equipment to perform at its best,” he says.
Ideally operators should check their tires’ air pressure daily, but Junkins allows that this can be impractical given the pace of construction, quarry and mining work today. At a minimum, she recommends weekly pressure checks and visual inspections. “Some of your bigger fleets have sophisticated air pressure and tire maintenance programs or pay a dealer to come in and take care of it,” she says. “Your smaller companies don’t necessarily have good programs, and yet they’re the ones who are failing tires and the ones who can’t seem to get tires.”
Visual inspections are becoming increasingly important in detecting tire cuts or damage while there is still a chance to repair them. “A lot of tires come out of service a month or more after they’ve had an impact because the cut starts at one point and then migrates inward,” Good says. “The operator says he didn’t hit anything, but the original hit may have happened two months ago.”
An experienced loader operator will keep his area clean and debris free to prevent rock cuts on the tires of his machine as well as the haul trucks.
Changing air pressure
There are times when the air pressure recommendations from equipment OEMs or tire manufacturers may not be the best for a specific situation, so it pays to consult your suppliers whenever conditions change. Some of these changes may include:
· Sites where equipment is going up or down steep hills, placing a lot of stress on different axles
· Increased loads on trucks or wheel loaders (sometimes this can be as simple as the weight difference between wet materials and dry materials)
· Loaders equipped with buckets or attachments that weigh more than the standard issue from the factory
Keep in mind that overinflation can be problematic too. “We have an SAE (Society of Automotive Engineers) standard that says when you overload a truck by 1 percent you have to increase air pressure by 2 percent up to a maximum air pressure increase of 30 percent on bias tires and 14 percent on radials,” Good says. But even if you follow these guidelines, the overinflation will increase the impact of rocks on the tires, make them easier to cut and prematurely wear out tread in the center of the tire.
Retreads to the rear
If you buy a wheel loader or haul truck with a set of new or nearly new radials on it, Good recommends you take the radials off the rear wheels and put retreads or bias-ply tires in their place and save the additional radials for use later.
“The rear tires don’t carry the load, they’re just there for the ride,” Good says. “There’s a lot of retreading going on right now. Before the shortage a lot of people would run a tire to destruction on the rear. Now they pull them with about 10 percent of the tread left and retread so they can extend the life.”
As a rule of thumb, retreads cost about half of what you’d pay for a new tire, and they’ll give you the same life, reliability and safety of a new tire as long as you use a quality retreader, says David Kolman, associate director of the Tire Retread Information Bureau. Additionally, there are wide variety of treads and compounds available to suit most any off-road application.
You can retread a good casing up to as many as five times, Kolman says, and new technology and materials have made it possible to repair tire cuts that were once considered unsalvagable. To pick a good retreader, Kolman suggests you ask your tire vendor, and call the retread company to arrange a visit. “Most will let you tour their plant if you call ahead. Look at the quality of their work and ask a lot of questions,” he says. You can also get more information on retreads at the TRIP website (www.retread.org), or you can call them at (888) 473-8732, or e-mail firstname.lastname@example.org.
Go with what you can get
As a temporary measure, contractors who can’t get any radials for their loaders and haul trucks are shodding them with bias-ply tires. This is not without complications and risks, says Junkins. “On haul trucks, radials are designed to go less than 30 mph and no more than 2.5 miles one way,” she says. But radials get pushed all the time and in most cases they have the capability of surviving. Bias tires don’t. A lot of the haul trucks can go 45 to 47 mph on a good flat road. Bias tires run hotter and at those speeds you build up too much heat.”
Good says he’s seen customers who when faced with this situation, take the top gear out of a truck just to make sure drivers don’t go too fast or too far on bias-ply tires.
In addition to distance and speed considerations, there are a lot of performance differences between radial and bias-ply tires. Before you decide to substitute bias ply for radial tires, consult with your tire vendor and equipment dealer. Make sure you’re not voiding any warranties, what you’re doing is safe, and you fully understand how this may affect productivity.
If you’re operating in conditions where you expect a certain amount of tire damage from rocks and debris, protecting your loader tires with a set of chains might be a good way to extend tire life. In the steel industry scrap and recycling yards use chains a lot, and they’re sometimes used in quarries.
Chains are expensive but you get almost no wear because the rubber never hits the road. Chains also prevent rocks from penetrating the tire. “I’ve seen big tires under chains on Cat 992 wheel loaders, and they’ll run a couple of years, which is phenomenal,” Junkins says. “A guy showed me a tire that had run 8,000 hours under chains and it still had 75 percent of its tread left.”
Rocks cut tires. It’s as simple as that. And in loading operations, quarries and mines there are only two ways to keep rocks away from tires – using a motor grader or loader to keep the roads and sites clean.
Motor graders are used in surface mines to keep roads clean and correctly profiled. The haul roads in these sites are engineered with specific curves and super elevations that take into account a number of variables, including the tires’ load carrying capacity. But unless drivers use their radios to communicate about rocks and debris in the road, it’s almost certain that these will find a tire. Another way to reduce this hazard is to avoid overloading trucks, which leads to spillage.
For loaders, the responsibility for keeping a clean site falls squarely on the operator. “A good loader operator is worth his weight in gold,” Rasey says. “Between loads he’ll police his area, moving the debris so that his trucks have a clean area to back into. He’ll also keep the pile neat so that he gets a good bite into it rather than running up on the pile and spinning his wheels. Their training and education is important and it will pay big dividends.”
Clean, well designed haul roads maximize tire life and prevent damage.
Stop tramming and long hauls
Another practice you should avoid is tramming – moving equipment long distances under its own power, rather than on a trailer. For a contractor in a hurry, tramming is a field-expedient way to move equipment. But even when the equipment isn’t carrying a load, if you go far enough or fast enough you will damage the tires.
Likewise for pick-and-carry operations with wheel loaders. Fundamentally, loaders aren’t
designed for long runs. And while some manufacturers offer beefier transmissions and cooling systems to stand up to the rigors of pick-and-carry applications, there’s nothing you can do to protect your tires from the heat generated under these conditions. The only way to avoid this hazard is to redesign your work sites so that you minimize the distance your loaders travel.
Caution with modifications
Although many contractors are tempted to add sideboards and tailgates to haul trucks and side plates to loader buckets, it’s almost always a false economy. Extra heavy loads slow down cycle times, increase fuel costs and machine wear and endanger your tires.
All the experts we talked to recommended avoiding modifications and sticking to the factory specifications concerning loads. Good adds that you should even calculate the weight of the mud that sticks to the underside of your haul trucks, which can add up to a ton of unaccounted for weight on big haul trucks.
When circumstances demand modifications such as bedliners or tailgates be sure you compensate for the weight these steel components add. Adjust the air pressure and factor in the additional cost of excess tire wear. (See chart on page 25.)
In it together
Tire industry officials emphasize they’re not running out of tires. It’s just that the demand makes the wait for new tires longer – a lot longer. “It’s not like it used to be, when you could place an order one day and get the tires next week,” says Tomas Bennett, market segment manager, Michelin North America. “You have to be looking several months out, maybe even six months, and anticipating your needs.”
The tire industry has realized nobody wins if this shortage isn’t managed as a problem that will require everyone to work together to solve.
“I’m sure all of our competitors feel the way we do,” Junkins says. “Every tire that fails early makes the shortage worse for everybody. So call us, give us your details and let us help you out. Everybody is predicting that it’s going to get worse this summer and probably much worse before it gets better.”
Sidebar: Choosing the right new tire
Most equipment owners and fleet managers have a good idea of which tires work best for them. If you’re getting ready to order new rubber for your machines it might not be a bad idea to rethink those assumptions with an eye toward maximizing tire life. What was considered an acceptable rate of tire replacement yesterday may prove risky today.
Heavy equipment tire types are designated by a letter and a number. The letter indicates the type of machine (E for earthmover, L for loader, G for grader and so on.) The number (typically 1 through 5) expresses the amount of tread vs. the amount of void on the tire.
The lower the number, the more open the tread. As the numbers go up, you get more tread and less void – more protection, but less traction. So, for example, if you’ve been satisfied using an L2 type tire on your wheel loaders despite the occasional rock damage, you may want to move to an L3 tire, pay the extra cost (more rubber in the tread) and sacrifice a bit of traction for the sake of preserving your tires.
You might also want to look at the aspect ratio of your tires. The aspect ratio is the ratio of the tire’s height to its width as measured in cross section. So a 100 series tire, which has an aspect ratio of 100, is as tall as it is wide – a 1:1 ratio. The 80 series tires are a little wider than they are tall with a height to width ratio of 80:100.
The 65 or 70 series “low profile” or “low aspect” tires (65:100 or 70:100 height-to-width ratio) are the fullbacks of tires. They put a bigger footprint on the ground and they lower the center of gravity of the machine, resulting in better braking, handling, stability and rimpull. Since slippage is often the cause of cuts and excessive wear on haul and articulated trucks these low-profile designs have been gaining in popularity over the 80- and 100-series tires in these applications.
Sidebar: 11 tire shortage to-dos
1. Call your tire vendors immediately, discuss the availability of the tires you use most frequently and put in an order now for the tires you need six to 12 months from now.
2. Get your dealers to set you up on a tire-tracking software program.
3. Establish an air pressure maintenance program with weekly or more frequent pressure checks and visual inspections.
4. Review haul road and jobsite conditions with operators and drivers to make sure they keep their areas clean and free from troublesome debris.
5. Invest in training for less skilled wheel loader operators.
6. Avoid tramming equipment over long distances.
7. Retread every tire possible.
8. Consider running bias-ply tires on the rear axles of loaders and haul trucks.
9. Consider low-profile/low-aspect tires in conditions where slippage is a problem.
10. Consider upgrading to more of a rock-type tire (from L2 to L3 or E2 to E3) in applications where rock damage is common.
11. Avoid machine modifications that increase load whenever possible.
Sidebar: Causes of tire failure
Worn out 7%
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