A method for the determination of optimal tooth modifications in spiral bevel gears based on load distribution, minimized tooth root stresses, and reduced transmission errors is presented. Modifications are introduced into the pinion tooth surface considering the bending and shearing deflections of gear teeth, local contact deformations of mating surfaces, gear body bending and torsion, deflections of the supporting shafts, and manufacturing and alignment of mating members. By applying a set of machine tool setting parameters, the maximum tooth contact pressure can be reduced by 5.4%, the tooth fillet stresses in the pinion by 8% and the angular position error of the driven gear by 48%, based on a spiral bevel gear pair manufactured by machine tool settings determined by a commonly used method.