Differential Ring Gear Tooth Nomenclature

The side of the differential ring gear tooth which curves outward, or is convex, is referred to as the "drive" side. The side of the differential ring gear tooth which curves inward, or is concave, is referred to as the "coast" side. The end of the tooth nearest center of the differential ring gear is referred to as the "toe" end. The end of the tooth farthest away from the center is the "heel" end. The toe end of the tooth is smaller than the heel end.