Magazine for the professional tire industry
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MTD August 2016 Choosing tires for 6x2s Fleets may be forfeiting tire life for improved fuel mileage By Jim Park I f I were a tire, the last place I'd want to be is a drive tire on a 6x2. e North American Council on Freight Efficiency's Confidence Report on 6x2s, released in January 2014, noted that operators can expect drastically diminished life from tires used on 6x2 drive axles. "Data from tire manufacturers and several fleets indicates that the usable tire life on a 6x2 drive axle is actually about one-third that of 6x4 drive tires," the report states. One-third. at's a lot of tire life to forfeit in pursuit of improved fuel mileage. W hat kills 6x2 drive tires? Mostly, it's torque. But it doesn't have to be that way. Defining a 6x2 In its purest form, a 6x2 chassis configuration is a three-axle tractor with power going to just one of the tandem rear axles. Put another way, only two of the six wheel positions are powered. Early versions of the configuration featured a dead axle that went along for the ride until it was needed for carrying capacity. Usually those dead axles were liable. Some were fied ahead of the driving axle (called pusher axles), while others were installed behind the driving axle (called tag axles). Most OEMs today offer what can comfortably be described as 6x2 configurations, but they are far from the 6x2s of old. e new generation of 6x2s began creeping into the market in about 2010. Already we're seeing OEMs and component suppliers differentiating their designs through traction control features, automatic load transfer mechanisms to improve traction, and liable non-driving axles to reduce rolling resistance and tire wear when lightly loaded. As with most major changes to truck designs, fleets remain wary about 6x2s. Many are reluctant to embrace the technol- ogy, despite the promise of lower vehicle weight thanks to the elimination of one heavy drive axle and improved fuel economy through reduced mechanical drag in the driveline. In fact, 6x2s represent about 4% of the 40,000-pound on- highway axle sales right now, according to Karl Mayer, director of product line management for rear axles at Meritor. "Sales have plateaued. We saw very lile growth in the market over the past Tire selection: 6x2 chassis 50