Inner Edge/Shoulder Wear
WARNING: This page is about a different car, the 2009 Ford Mustang. However, it is still accessible from the selected car via links, so may be relevant.
Inner edge (or shoulder) wear occurs on the inside edge of the tire and is usually caused by excessive toe-out and/or excessive negative camber. If the tread depth of the outer shoulder is at least 50% greater than the tread depth of the inner shoulder, the tire is experiencing inner edge/shoulder wear. To determine whether tires have this type of wear, visually inspect the tires. In some instances, you may need to measure the tread depth of each rib and compare it to that of the shoulder.
NOTE:
RF tire shown, others similar.