CHOOSE BOTH. VehicleServicePros.com/10119745 Tire evaluations By Reuben DeBolt, Commercial Technical Services Manager, Roadmaster, Cooper Tire Tires constantly evolve, applications vary and tire price points don’t always tell you the “life” you should expect from your tires. Just because you pay more for a tire doesn’t mean you will get higher mileage and more retreads. When it comes to tires, the only way to determine what’s best for your application is to test them yourself by developing an on-going tire evaluation program and comparing the tires you currently run with a possible newcomer to your fl eet. Unlike a tire company that is testing products daily with dedicated technical professionals and sophisticated equipment, most fl eets do not have the capability or bandwidth to conduct exhaustive testing. Yet, you can still do a valid evaluation within a fl eet and get results that give you confi - dence in what to expect from selected tire brands. To conduct an apples-toapples comparison, run likebrand and like-model tractors or trucks, the same age, with the same specs. In addition, drivers comparable in skill level should run the trucks. Drivers can impact tire performance in subtle ways. Routes and loads should be identical, or as similar as possible. Choose dedicated long-haul routes or similar types of service for a regional or local operation. STEER TIRE EVALUATION Outfi t four trucks with your new evaluation steer tire and outfi t another four with the steer tire you’re currently running for a headto head analysis. There are two reasons to run at least four vehicles: 1. To get a good average wear rate considering any variation in vehicles, routes or driver. 2. If you lose a tire due to a road hazard, you will still have three vehicles left running. DRIVE TIRE EVALUATION In this evaluation, you can use one vehicle to test two brands of tires. The only caveat is that their diameters need to be within 1/4” of each other. To put that into perspective, you can run one drive tire with 30/32nds of tread depth and have the competing drive tire within plus or minus 4/32nds of that fi gure. With this evaluation, you can run two trucks with eight wheel positions. The key is doing an X-pattern (or cross axle) on the two rear axles. However, don’t run the tires identically on the two trucks. The right rear outer tire historically wears faster than any other drive position tire due to a higher percentage of right-hand turns, which can cause scrubbing. Be sure to have brand X in that position on one evaluation truck and brand Y on the next truck. Also, note that tires on the trailing axle typically wear about 20 percent faster than tires on the forward axle. MAINTENANCE PRACTICES Once tires are mounted, each vehicle should undergo a total vehicle alignment on the front and rear axles. It’s important for drivers to conduct proper pre- and post-trip inspections, including checking tire infl ation. Drivers also must keep their eyes and fi ngers on the tires to inspect for wear. A weekly fi ngertip diagnostic – simply running a hand over the tread – can detect signs of irregular wear. If drivers detect early signs of irregular wear, your fl eet can fi x the underlying problem and continue with the evaluation. Be sure to keep A weekly fi ngertip diagnostic – simply running a hand over the tread – can help detect signs of irregular wear. Photo courtesy of Roadmaster a record of any wear issues and vehicle adjustments. EVALUATION PERIODS Evaluation units should be checked every 30,000 miles or every three months, whichever comes fi rst (75,000 miles for steer tires). The fi rst item to analyze is tread wear. When checking the tire, you should have three points for gauging across the tread face – the outside, middle and inside of the tread. Again, a fi ngertip diagnostic should be conducted as well, and any signs of irregular wear reported. If the irregular wear is found to be severe in the drive or trailer position, rotate the tires on the front rear axle in cross axle design. For example, LRI and O (Left Rear Inner and Outer) to RFI and O (Right Front Inner and Outer). At about 75,000 miles, you should have solid wear data on your steer tires. Drive and trailer tires should give solid data at about 90,000 miles. TREAD WEAR RATE Now that you have data on how much tread is worn on your tires, how do you: • Calculate your tread wear rate to project total miles to removal? • Factor in casings and retreadings? • Determine cost-per-mile? Reuben DeBolt is the commercial technical services manager for Roadmaster, a brand of Cooper Tires (us.coopertire. com). Online Exclusive Complete recommendations for performing an apples-to-apples tire comparison can be found in Roadmaster’s whitepaper on how to conduct a tire evaluation program, at: VehicleServicePros.com/12201070 Heavy Duty | VehicleServicePros.com ❚ JUNE 2016 ❚ FLEET MAINTENANCE 19
FleetMaintenance_June_2016
To see the actual publication please follow the link above