I cannot see how the rubber could wear like that. My first response shows the tires with similar but less advanced step in my tire. So i think it a factory defect. The tire will wear down to be level with the low half. Since you have good traction now just keep using it as is. When you get a new wheel then check it carefully to ensure there are no imperfections.Hey Town....being that you seem to have some knowledge of my issue, I would appreciate any help you could offer. I am mechanically inclined, but this one has me baffled. I understand the disc wearing at an angle, but not "stepped" like this.