A normal, neutral gait will see heel wear at the middle to outside edge of the heel, on the little toe side of the foot.
Over-pronators will see more heel wear in the middle of the heel and perhaps even toward the inner edge of the heel (the big toe side). Their shoes may even tilt inward when placed on a flat surface.
Supinators or under-pronators will see heel wear all along the outer edge of the shoe. When placed on a flat surface, their worn shoes may tilt outward.