January 1, 2009
Careful attention to tire and rim maintenance and retreading often pays off.
by Bob Joyce and Wilhelm H. Brau
Jack Dutcher, national manager, education and training for Bridgestone Americas Off Road Tires, describes off-the-road (OTR) tires as a production asset, adding, “With proper selection and regular maintenance, tires can play an important role in minimizing costs while maximizing production.” In today’s business environment, it’s important to go one step further. Industry corporations are changing corporate cultures and accepting environmental responsibilities to conserve resources. C2G no longer stands for cradle-to-grave, but cradle-to-green. Proper tire selection now includes selecting tires with rugged casings that outlive the tire tread in order to be retreaded.
An operator’s first critical decision is to select the proper OTR tire. Just a few of the determining factors include selection of radial or bias; heat resistant or cut resistant; L-4 or L-5; smooth tread, half tread, or rock tread; job site conditions; material densities; and type of equipment.
Aligning an operation with a dedicated OTR tire manufacturer and service dealer can make the process less painful. Bridgestone America’s Russ King has a theory called the “Three-legged stool.” The client (end-user), servicing dealer, and the tire manufacturer make up the three-legged stool. “It takes the resources, and commitment and partnering of all three to maximize production and minimize costs,” Russ says.
For example, major brand OTR tires have a ton-mile-per-hour (TMPH) rating. The TMPH is an expression of the working capacity of the tire and is also a function of the maximum allowed internal operating temperature of a tire. It’s no secret; heat is a tire’s worst enemy. In simplistic terms, the TMPH rating is a heat index.
Using the resources of field engineers and product managers, an OTR tire manufacturer can perform an on-site TMPH study. Several factors – including load, speed, distance, number of cycles, and type of equipment – are part of the formula to determine the operational TMPH at a given job site. Once the job site TMPH is determined, the correct tire can be recommended for maximum performance. If the tire’s TMPH rating is lower than the operational job site TMPH, the tire is not suitable for this application. Under these circumstances, a change in compound, construction, or tread pattern should be considered. However, if the tire has a higher TMPH rating than the job site TMPH, the tire is suitable for this application.
Job site conditions also can be changed or modified to adjust the operational TMPH. Speeds and loads can be reduced, but field experience indicates that this is unlikely. In fact, chances are better that both loads and speeds will increase.
Today’s technology unlocks potential; as a result, a TMPH study can be done very efficiently and quickly without disrupting production or other normal job site activities. A job-site TMPH study is essentially end-user due-diligence and provides information that helps operators make informed business decisions.
Selecting the proper tire is also important if an operation is to realize the benefits of retreading. Consider choosing major tire brands when purchasing new tires. A tire’s casing is approximately 75 percent of the tire construction weight. Major manufacturers have invested heavily in research and development of premium casings, which are likely to be better candidates for retreading.
An authorized off-road tire dealer can help operators choose tires that are good candidates for retreading. Casings with few injuries and no signs of separations are most desirable. Casings with low hours of operations are preferred for retreading as casings with high hours often tend to fatigue and fail during the retread curing process or during normal operation after retreading.
Just as it is important to select the correct ply rating and load range for new tires, it is equally important when retreading to match the ply rating and load range of the original tire with the retread design. Servicing retreading dealers may be the best source of information for proper retreading procedures.
Even with today’s enhanced technologies, state-of-the-art manufacturing processes, and other checks and balances, the human element remains paramount to proper tire maintenance.
It’s not puffery to say that a sound inflation program is not only the foundation for good tire maintenance, but it is also the single most important factor with regard to tire performance. Correct air pressure is determined by several factors. Load, speed, type of equipment, and operating conditions are the primary factors. Ideally, operators should familiarize themselves with the guidelines set forth by the tire manufacturer when determining inflation pressure. This is especially true before any consideration is given to stepping outside of the tire manufacturer’s parameters.
A tire inflated to 70 percent of its recommended air pressure will wear out or most likely fail during the first 50 percent of its life. If that does not get your attention, nothing else will! A couple of important rules to follow involving air pressure include the following:
Other regular maintenance activities should also include proper tire matching, rotation, removal of stones/rocks wedged between dual tires, and proper repairs. All of these maintenance practices will enhance tire performance. Also, fuel and oil leaks exposed to tires will soften the rubber, promote premature wear, and potentially cause failure.
Several years ago, Kenn Bush wrote an article on OTR tire maintenance and repairs entitled “Forgotten Heroes.”
Unfortunately, wheel/rim assemblies and related components fall into the forgotten hero category. Each year, folks are killed when working with wheels and rims.
Rimex, a major manufacturer of earthmover wheels, notes that rims and wheels, as well as related support parts, reach a fatigue stage at some point. Yet, the consensus among many end-users is that they will last the life of the vehicle. In some instances, this may be the case. However, even though rims and wheels are strong and durable, they have service life limits. Rust, fatigue, and damaged parts are major causes for out-of-service conditions. Fatigue cracks in the rim base and/or flange are common failures usually after thousands of hours of service. Earthmover rims are subject to extremely high stress due to high inflation pressures, torque loads, shock loads, steering and braking force, and the applied load of the vehicle.
Proper, preventive maintenance of rims and related hardware is vitally important to proper tire service. Cleaning and inspecting is essential to rim maintenance. Sand blasting and wire brushing are two acceptable cleaning methods. Once cleaned, inspect for stress cracks, broken welds, or other damage. Don’t forget basic valve maintenance and never heat or weld on rims, wheels, or their support components.
The Mine Safety and Health Administration (MSHA) publishes a Tire and Rim Safety Awareness program. It is an excellent publication, full of information regarding tire and rim safety, maintenance, performance issues, operational conditions, and more. Operators should become familiar with this free publication. It is a wonderful reference for annual MSHA refresher training. Check out MSHA’s Web site at www.msha.gov/S&HINFO/IG60.PDF. Look up catalog MSHA IG-60. One positive note: mine deaths fell to an historic low in 2006 in the metal/non-metal mining sector. Industry representatives cited training programs as the key factor in reducing fatalities.
Tire tracking software program
Another way to realize big dividends from an off-road-tire maintenance program is being able to follow the money. If you do not have data for cost per hour or cost per ton moved, reasons for failure, budgeted or forecasted demand, data on tire performance and optimal retreading intervals, or any number of other key data management points, it is very difficult to demonstrate the cost savings of proper tire maintenance and retreading.
As stated earlier, technology unlocks potential. When it comes to OTR tires, a user friendly, tire tracking software program, such as Bridgestone America’s TreadStat program or those offered by other major tire manufacturers, does exactly that.
In today’s competitive environment, there is no compromise for operating at the lowest cost possible. The right tire tracking program is a management tool that will support this goal and provide data that will enable operators to manage this major expense of doing business.
“Over the years, there has been a major shift in the aggregate industry towards a fact-based tire management program,” says Chris Rhoades, Bridgestone’s product manager for the TreadStat program. “Today, all of the major aggregate producers have a TreadStat implementation underway and are reaping the bottom-line payoffs: reduced cost/hour and increased productivity.”
Tire tracking programs can provide reports with necessary key performance indicators that give plant managers the information they need to run their operations more effectively, he notes. Online software options allow servicing dealers and end-users to manage tire fleet assets and maintenance at multiple locations at the touch of a button.
Going green is often considered an expensive proposition that robs money from the bottom line. Major tire manufacturers recognize the importance of the bottom line by offering C2G solutions that include retreading of premium off-road tire casings. Retreading reduces the costs of aggregate operator’s off-road tire fleets, while providing equal service and safety to that of new off-road tires.
Retreading is recycling. It involves the re-use of most of the original tire “casing” and replaces the worn tread with a new tread, delivering the same balance of performance as the original product. The Environmental Protection Agency cites the following benefits of retreaded tires:
While there are more uses for scrap tires than ever before, the best way to deal with scrap tires is to avoid generating them – i.e., retread them. And, according to the Tire Industry Association (TIA), retreading produces 30-percent less CO2 than new tires.
Coupling the expertise of a trained dealer and the use of tire and rim management software to efficiently track wear rates and damage, premium casings can be preserved for retreading. Knowing the right time to pull the original tires out of service, with the casing still suitable for retreading, can stretch an operator’s initial tire investment and lower tire costs. Proper maintenance of wheel/rim is also important because of how it can affect the bead area. Corrosion of wheel/rim can cause the bead area to separate, making the tire unacceptable for retreading.
Armed with the right information and expertise, today’s operators can not only go green, but also save green, and that’s what it’s all about.
Bob Joyce is a senior corporate account manager for Bridgestone Americas Off Road and Wilhelm H. Brau is general manager Continuum Retread & Recycle Solutions for Bridgestone Americas Off Road.