By Koen Vandermeersch
Tire rotation on off-the-road equipment is a maintenance activity that has been around for decades. Fleet owners, tire service providers and tire manufacturers alike have been convinced of the usefulness of tire rotation turning it into an unwritten rule before it became a necessity. A necessity indeed: when you don’t have tires to run your trucks, they go up on blocks and their production rate is turned to zero. A potentially heavy financial burden.
Global Shortage
The global premium mining tire shortage of which symptoms were visible as early as 2004, surprised many, including all of the largest mining companies. None of them had anticipated the effect of the mining industry’s acceleration on the availability of a key consumable.
With profit margins on off-the-road tires being less than sustainable until the shortage, none of the tire manufacturers had invested in production capacity growth nor had any of them anticipated the increased demand. The off-the-road tire shortage became a reality and all means were used to extend tire life to the maximum in order to keep the trucks running.
Overall, a mixture of smart initiatives, doubtful practices and at times dodgy intermediaries could still not prevent multi-million dollars of production value from being lost because of the absence of a basic truck component. And of course, there was tire rotation.
Far from being a doubtful practice, tire rotation has demonstrated in many situations to be an ideal measure for extending tire life successfully. On truck steering axles, turning tires on their rims often combined with a swap between the front left and right positions, has helped to combat sloped wear or heel/toe wear as a result of haul road conditions or vehicle configuration, effectively increasing the tire life potential.
Rotating partially used tires to the rear axle after a certain life or wear on the front axle is usually referred to as a rotation policy. The moment on which tires are rotated is often determined by the overall tire life potential of the site.
Correct matching of duals across the rear axle is a condition to meet the objective of extended life. Whilst safety remains one of the main arguments to move tires from front to rear, the two-rotation policy often aims at generating a tire consumption flow that looks for scrapping tires with the least tread remaining and the longest life on the clock. That provides the lowest cost per tire unit, which is, from the tire perspective, a respectful objective.
Uptime vs Tire Life
During the global OTR tire shortage, hours were spent on saving valuable millimeters of rubber, and with good reason. It reduced the risk of parking trucks.
Now that the shortage is long behind us, is it still worthwhile to turn or rotate tires and look for the longest tire life? How does the lost value of truck downtime compare with the cost saving effect of tire rotation? Times have changed and focus has shifted to surviving the downturn and being ready for when things change for the better.
Improving tire management should allow for questioning the obvious. In the current business environment, the obvious is no longer tire life alone. It primarily is increased site productivity and cash-flow management while maintaining – or, preferably, improving – safety levels, that require attention.
Truck utilization, and thus production, is directly affected by the tire rotation policy of a site. An average tire change duration of 2.5 hours in a 25-strong truck fleet can easily generate the equivalent of one parked truck for two months (2.5 hours downtime x six tires x two rotations/tire/year x 25 trucks = 750 hours) just by looking to optimize tire life through tire rotation.
If we suppose that tire rotation improves the average tire life by 20 percent on a $30,000 tire, savings generated could amount to $900,000 on an annual tire budget of $4,500,000. On the other hand, depending on size and ore type, truck production value could return +1 million $2 per month.
Over a two-month period that would quickly offset the annual tire budget savings. In any case, if an average truck in your fleet generates more production value than what you can save on tires, it is worthwhile to examine an alternative to the existing tire rotation policy and to rebalance cost versus return.
Koen Vandermeersch has a bachelor’s degree in transport economics. He has 24 years of experience with Michelin. He has worked in the off-the-road and industrial tire business since 1998 and has built up extensive managerial and operational expertise across the world, managing a variety of services, innovation, sales, marketing, technical and R&D projects. www.102psi.com