Getting the most out of truck tires

Most truck tire failures are caused by contact with rocks spilled on haul roads, in loading areas or at dump points. 

Machines that remove spillage and a communication system that promotes fast action are beneficial to operations. But in addition to a good mine design, proper loading and operating techniques are necessary to reduce the need to clean up and replace worn tires.

Loader operators play a key role in extending the life of truck tires. Centering loads properly in truck bodies and not overloading trucks allows tires to work within their intended load limits. Correctly sized and properly placed loads are also less likely to lead to rocks on roadways.

Training motor grader operators about proper road construction and maintenance is important, as well. Water truck operators should receive a thorough training, too, as watering to suppress dust helps to maintain compaction in most climates.

Still, too much water can create slippery conditions, with water increasing the likelihood of tire cuts from sharp rocks. Using intermittent watering patterns on slopes can reduce the risk of tire slippage.

Additionally, do not overlook dump areas to optimize truck productivity and tire life, either. Dump areas should have smooth floors allowing trucks to maintain speed until they reach the dump zone, where they enter parallel to the edge or crusher opening and brake in a straight line before turning, stopping and reversing to the dump point.

Building and maintaining haul roads

For rigid-frame haulers, road design and maintenance has a huge impact on haulage cycle efficiency, costs and production. 

Proper road design is the first step to ensure good truck productivity and low operating costs. Critical elements are grade, cross slope and superelevation of curves. Goals should be to maintain proper weight distribution of the load and minimize lateral forces on tires. The same design that enhances truck productivity also reduces component wear and optimizes fuel burn, as trucks remain stable at optimum speeds.

The steeper the grade, the more weight bears on the rear tires. So a goal should be to keep the weight distribution at about one-third on the front tires and about two-thirds on the rear duals. Ideally, the grade would not exceed 8 percent. The grade should be constant and the road smooth to minimize rapid weight distribution changes, minimize transmission shifts and maintain a higher average speed. Such roads also promote smooth braking when trucks are returning to the loading area.

Roads must also drain properly to reduce slippery conditions and to help minimize rolling resistance. On flat terrain, the minimum cross slope maintains drainage for the expected rainfall at mines. If conditions permit, consider a 2 percent constant cross slope. Four percent cross slope can be used in rainy areas. 

Alternatively, roads should be crowned slightly to drain water to both sides. On grades, minimal cross slope or crowning is needed because the grade itself helps to direct water off the road.

Also, corners should have the maximum practical radius to help maintain speed and to minimize side force on tires. Side force generates heat in tires and reduces casing life. High-side forces scuff tires and accelerate tread wear, too. Corners should be constant and smooth to reduce steering corrections, operator fatigue and component wear.

Information for this article adopted from Pit & Quarry University. Visit Pit & Quarry University online at pitandquarry.com/pquniversity