The recent shortage of earthmover tires has taught contractors a lot about the role tires play in the overall cost of doing business. "The tire shortage that plagued the industry for the previous years has lightened significantly," says Cara Junkins, director of sales and marketing, Titan. "During that time though, a lot of operators learned how to watch tire costs and do what was necessary to elongate the life of their tires."
Even though the shortage for certain sizes is beginning to ease, the influence tires have on overall operating costs remains, since they greatly affect fuel costs, productivity and vehicle performance. "Site operators who are looking to increase their overall profitability can do so by taking an easy, yet often overlooked step ? taking care of their tires," says Steve White, earthmover market segment manager, Michelin North America, Inc. "Well-maintained tires allow machines to stay operating longer, increasing productivity and profitability. Not to mention that properly maintained tires help increase safety."
Select for conditions
Fuel has always been near the top of the expenses list. To help control these costs, it's important to understand the role tire selection and maintenance play in fuel economy.
"Fuel economy is all about rolling resistance," says Barry Rexroad, senior manager, OTR engineering, Bridgestone Firestone. "Rolling resistance is basically how freely a tire rolls and how much inertia, or energy, you have to overcome to keep it rolling. It's a little harder to measure in an earthmover tire than it is with a passenger tire because they run on so many different surfaces, such as dirt and mud. How loose or how packed the soil is changes rolling resistance. If the surface is very soft, very rough, etc., it takes more energy (i.e., more power) from that vehicle to keep the wheels turning."
Selecting the right tire for the conditions will help to increase fuel economy, says Junkins. If you run mainly on compacted surfaces, choose a tread pattern designed for that application. If you run mostly in the mud, choose a pattern with extra traction. However, keep in mind that the greater the amount of rubber, the heavier the tire, and therefore, the more energy (fuel) it takes to move it. "Although it plays a relatively small role in fuel economy, it's something to consider," she says. "So don't select a tire with a deep tread unless you really need it."
Maintain proper pressure
While tire design and tire selection affect fuel economy, tire inflation pressure has the greatest influence on rolling resistance. "Tires are designed to work most efficiently at a specific pressure for the necessary load, providing the proper amount of vertical deflection," says White. "A properly inflated tire puts the correct footprint on the ground to provide traction and to reduce wasted energy caused by wheel spin. A properly inflated tire is also more efficient in regards to the energy needed to move the equipment."
Issues arise when tires are over- or under-inflated. "Under-inflation will increase fuel consumption due to increased rolling resistance," says Arve Opperud, Caterpillar, Inc.
"Over-inflation wastes energy by bouncing equipment upward, rather than propelling it forward," adds White. "And it increases energy wasting wheel spin."
Correct inflation pressure is based on load. Work with your local tire dealer or equipment manufacturer to determine the optimum pressure. Essentially, you will want to set the pressure for the heaviest load, then check it regularly, ideally every morning, to ensure the proper pressure is maintained. "You want to cover the situations where the bucket is completely full," indicates Rexroad. "Also consider the density of the material you're moving. If you're unsure, check with your manufacturer and use scales to weigh the equipment with different materials."