Some say that too low of an air pressure with a knob pattern like that where you have one knob in the center for every other or two knob rows can push that single knob in and put the wear on the multi knob row. From my experience that wear looks more like wear from braking and on a front tire (rear wheel drive of course) and that with weight transfer to the front during braking and lower than owner's manual air pressure could cause that kind of wear. No big deal those tires can be found for a reasonable replacement price.