Overdrive Magazine | Trucking Business News & Owner Operator Info
Issue link: http://read.dmtmag.com/i/911782
48 | Overdrive | December 2017 WAR ON WEAR Properly maintained air pressures will extend the life of the tread and the casing for retreading. When checking infla- tion levels, make sure that the measurement tools are calibrated properly. Usage conditions can cause a pres- sure gauge to lose accuracy beyond the 2-psi tolerance range recommended by man- ufacturers. With dual tires, an inflation pressure mismatch of greater than 5 psi will result in differ- ent circumferences, resulting in irregular wear and possible premature casing fatigue. With steer tires, "a differ- ence of 5 psi will cause the vehicle to pull to the side with the lower pressure," Webb said. 3 Improper mounting Tires that are mounted incor- rectly never stand a chance to reach their wear potential. "A tire that has not been prop- erly seated can create imme- diate irregular wear patterns and ride, handling and vibra- tion issues," Clauer said. If the tire is not seated properly to the wheel flange, the tire and wheel assembly will have an "out-of-round" posture, creating wear, he said. "If the tire bead doesn't fit into the wheel properly – for example, if the tire was not sufficiently lubed during installation – it will not prop- erly center onto the wheel flange," said James Matarelli, a Continental sales manag- er. "This prevents the tread from lying flat as the tire rolls forward and backward and causes uneven wear on the shoulders." Mounting tires from dif- ferent manufacturers also can cause an unintended mismatch. "In some cases, tires can have identical tread depth but a different overall diameter due to engineer- ing differences," said Travis Despain, a sales manager for Continental. Diameter differences of larger than a quarter-inch can create scrubbing patterns for the smaller of the two tires, Perrow said. A differ- ence as small as 4/32nds in tread depth can cause prema- ture wear. Carnegie said if one tire in a dual position requires pre- mature replacement, the ideal practice is to replace both tires with matching new tires. 4 Tire imbalance and alignment Wheel balancing can reduce ride complaints and vibra- tions, but it's also instrumen- tal in prolonging tread life and eliminating irregular wear. While balance proce- dures and equipment vary, Clauer recommends doing it with the tire remaining on the vehicle so the tire, wheel, hub and brake rotor/drum are balanced as a unit. Alignment refers not only to the various angles of the steer axle geometry but also to the tracking of all the vehicle's axles, including the trailer, Webb said. Irregular wear is most visible with the steer tires, so that's the best place to start when diagnosing alignment issues, said Rod Conner, a field services manager for Continental. However, align- ments at all wheel positions should be considered at each inspection and service cycle and when tires are replaced. "With 18-wheelers, a tra- ditional front-end alignment isn't always enough," Perrow said. "Drive axles must be aligned, too, making sure they are perpendicular to the chassis and, with tandem axles, parallel to each other." Trailers take a beating but are usually the last piece of equipment to receive any attention, Clauer said. "Trailers are subject to tire A tire that runs in extreme heat during the day and sits in much cooler conditions at night could show varying levels of air pressure.