This could be driving habits to. If you tend to corner faster the weight transfer to the outside tire can cause the tire to roll over a little more and wear quicker. I tend to drive this way and I do notice that my tires do wear a little more on the outside than the inside. I rotate every 5K miles and it has never been a big problem for me.
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2008 Ram 3500 SLT QuadCab LB SRW 4x4 6.7L G56 Light Khaki
DiPricol Optix(Pyro/Boost/Diff Temp), S&B CAI, Line-X, B&W Turnover Ball, ProTech, PacBrake Air Springs, HBS 2" leveling kit, MagHytec Rear, Willmore Wheel-to-Wheels, High Idle enabled, JakeBrake EB switch, 276hp 510ft-lb