Outer Edge/Shoulder Wear
WARNING: This page is about a different car, the 2012 Ford Pickup. However, it is still accessible from the selected car via links, so may be relevant.
Outer edge (or shoulder) wear occurs on the outside edge of the tire and is usually caused by excessive toe in and/or excessive positive camber. If the tread depth of the inner shoulder is at least 50% greater than the tread depth of the outer shoulder, the tire is experiencing outer edge/shoulder wear. Visually inspect the tires to determine whether the tires have this type of wear. In some instances, the tread depth of each rib may need to be measured and compared to that of the shoulder.
NOTE:
RF tire shown in illustration, others similar.