| Heavy Duty Tire forensics By Tim Hume, Technical Engineer, Yokohama Tire Corporation Lessons from a tire scrap pile More importantly, the information hidden in those “junk” tires can be the key to reducing your fl eet’s tire costs – provided that a serious eff ort is made to squeeze information out of the pile. TIRE INSPECTIONS Th e core knowledge that will be used for improving costs is gained through tire inspections. Th e job is going to be dirty, so it is advisable to wear gloves. Some tools that will be useful in getting the best results from your inspections are: 1. A tread depth gauge. 2. An awl to probe punctures and separations. 3. Pliers to “open” cuts. 4. A tire crayon to mark fi ndings. 5. A clipboard to record fi ndings. If there are a large number of tires to go through, it’s a good idea to have a helper. Th e job will go faster if you’re not putting down your tools and picking up a clipboard aft er every tire inspection. “I’ll inspect, you write” is a good strategy. Possibly the most important tool when looking at out-of-service tires is a conditions guide. Yokohama Tire Corporation has a few common conditions photographed and explained on www.Yokohamatruck.com. However, a more exhaustive resource is Technology & Maintenance Council’s Radial Tire Conditions Analysis Guide. For many years, Yokohama and other tire manufacturers have collaborated with fl eets and service providers to compile an excellent “What caused this?” manual. Th e intended user is a fl eet manager and the book is easy to use. Simply fi nd a picture that looks like the tire you are inspecting and then read about the likely causes and appropriate countermeasures. Don’t be surprised if the guide tells you that some tires can be returned to service. DETAILS As you inspect tires, the more information you have, the better. Knowing the vehicle ID and tire position can be very benefi cial. For example, steer tires from the same vehicle can be compared to identify a misalignment condition. Dual tires that have vastly diff erent appearance can indicate that they were running at diff erent pressures. Knowing the removal mileage is equally important. A steer tire irregular wear condi- Before I share my thoughts on scrap tire analysis, let me state that I hate the phrase “scrap tire pile.” Th e phrase conveys the idea that the tires in such a pile don’t have much value. Nothing could be further from the truth. First, if you look through enough tire piles, you’ll fi nd that many discarded tires are actually fi t for continued service. Negligence and haste can cause many useful tires to be mixed up with those that should be discarded. The core knowledge is gained through careful tire inspections and determining what caused the out-of-service conditions. Photo courtesy of Yokohama Tire Are your tires ready for winter? By David A. Kolman, Editor Winter weather places additional stresses on vehicles. The way to help avoid breakdowns is to properly prepare for colder temperatures and adverse driving conditions. Here are some tips from truck tire manufacturers. Inspect. Give tires a thorough going over, looking for any signs of damage, such as uneven wear, punctures, cuts, cracks, bulges, splits, etc. Tread depth. For winter weather driving, the more tread depth the better. A best practice is to exceed the minimum tread depth standards. Have at least 4/32” tread depth in every major groove on front tires; 2/32” on other tires. If any tires are close to these limits or are beneath it, consider replacing them. Air pressure. Regardless of the weather, maintaining proper air pressure is critical for getting the most performance out of a tire. Tire air pressure should be checked regularly during the winter weather season because tire pressure decreases by about 1 to 2 lbs for every 10 degrees F drop in air temperature. Infl ation. Having correctly infl ated tires in good condition is essential. Underinfl ation – the leading cause of tire failure – creates excessive stress on the tire due to increased sidewall defl ection, resulting in erratic wear. Over-fl exing generates heat, causing carcass fatigue and deterioration. Overinfl ation causes a tire to be stiff and unyielding, making it more susceptible to damage in the form of shocks and rapid, uneven tread wear. Cold tires. Always check air pressure when tires are cold – meaning not hot from driving, using a reliable pressure gauge. 20 FLEET MAINTENANCE ❚ NOVEMBER/DECEMBER 2016 ❚ VehicleServicePros.com
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