Not sure, but I wonder if you have the tires properly inflated. With the weight of the ISB you need to run about 70 psi in the tires on the steering axle. If you have sufficient inflation, then I don't have a clue of the cause of this.
Can't tell by the pictures but is it only happening on the inner or outer edge of the tire? If so then it is what is called heel-toe wear and is caused by incorrect toe setting. Typically only happens to either the inner or outer edge depending on how the toe is set. If it is happening to both edges then something is worn and causing the toe to change.
If the whole face of the tire is like that then you have a shock, ball joint or balance issue.
A forum community dedicated to Dodge Cummins Diesel truck owners and enthusiasts. Come join the discussion about reviews, drivetrain swaps, turbos, modifications, classifieds, builds, troubleshooting, maintenance, and more!