Opinion: Handling Tire-Management Issues
By Bob Rutherford
Founder, Trucking Industry Consultant
Rutherford & Co. Consulting
The reason I am making this bold statement is that not one fleet follows the tire manufacturers’ inflation charts to the letter. There are many reasons for this, but a cost-effective solution could be just around the corner. The problem is these charts relate axle load to tire pressure.
As an example, one chart would have an axle load of 10,520 pounds, requiring the tires on that axle to have a tire pressure of 85 pounds per square inch. When that vehicle picks up a load, the weight increases on that same axle to 14,780 pounds, and someone is supposed to know to increase the tire pressure on that axle to 130 psi. Most fleets take a best guess and shoot for 100 to 120 psi and very rarely match the charts for maximum tire life and fuel economy.
Fleets feel it has been a good day if they kept every tire at its target psi, which is based on the maximum load their vehicles might encounter.
The good news is there’s a solution to this tire-management issue.
I would estimate that about 95% of the technology needed to solve this problem exists. The load-cell technology, which indicates what the load is per axle, is sold as onboard scales and has been around for years.
A more recent piece of the needed technology that has been developed is the individual wheel-end air compressor. These pumps can both raise and lower the air pressure in the tires on a wheel end.
The missing technology is the computer and software interface, which would measure axle weight and indicate what the required tire pressure should be. It then could adjust the air compressor to maintain the proper psi setting.
The beauty of such a system is each axle — the weight of which varies with vehicle configuration — could be at the correct psi.
Thousands of trailers already have centralized automatic tire inflation systems. What would it take to install the load cell technology and the computer interface as a retrofit? My guess is the technology would be installed only on trailers with high annual mileage and would need only the load cells and the interface.
Another issue where current technology can improve a tire management program is wheel-end balancing. The great thing here is no further engineering is required! The technology of centrifugal balancing has been around for many years and should have been standard equipment on all commercial vehicles. The only reason it has not caught on is a lot of misinformation about tire balancing versus wheel-end balancing.
Centrifugal balancing systems zero out any wheel-end component — axle, hub, brake drum, tire wheel and bearings — that is out of balance. The results are longer tire life and lower vibration.
As the trucking industry moves toward both lower-rolling-resistance tires and wide-base tires, the issue of getting maximum life from the tire, vehicle and the driver are becoming the bigger issues.
This attitude I encountered a while back cannot continue. I once had a conversation with a major fleet’s tire manager about using a centrifugal balancing product and presented to him that we had clients that have extended tire life by 25% in their operations.
His response floored me. He told me that they benchmark against other fleets, and they are where they want to be. I said the thing about benchmarking is you want to be better than the benchmark. Wouldn’t you have a much better tire program if you get 25% better tire life? He accused me of not listening as he told me one more time; they are where they want to be on tire life!
There are two broad categories of these centrifugal balancing systems. In one category, the onboard-the-vehicle systems have a part number and become a part of the vehicle’s bill of materials. This will become a big issue for the OEMs as we get closer to the 2017 fuel-economy greenhouse-gas requirements.
The other category is products that come in buckets and bags and are installed inside the tire. Not really being part of the vehicle, this category of balancers tends to disappear at the first tire change. This category also has an issue with field replacement, as most service trucks do not carry service inventory.
Another issue is a tire manufacturer’s recommendation to fill its tires with only clean, dry air.
Because of tough fair-trade laws, no tire manufacturer has banned the use of these products; however, all have published “caution” technical-service bulletins.
The trucking industry can start saving billions of dollars in fuel and tires tomorrow by studying and picking which centrifugal balancing system would work best in its operations. Secondly, call your OEM suppliers and ask them to provide you a wheel-end psi-management system that operates based on axle weight.
Rutherford & Co. Consulting, in Franklin, Tennessee, contracted with Auburn University in Opelika, Alabama, in 2007 to help the school’s Program for Advanced Vehicle Evaluation become more involved with the trucking industry.
