There are basically three angles that encompass a front end alignment. Caster is the tilt of the steering axis (king pins) forward or backward and it does not cause tire wear under normal conditions. The caster angle on a Beaver is not individually adjustable without bending the axle, so it is rarely changed as part of an alignment. Caster is sometimes adjusted on both front together by using tapered shims between the axle and it's mounting to change handling characteristics.
Camber is the tilt of the steering axis in or out at the top. This angle can cause tire wear if it is excessive, but adjusting it on a Beaver requires bending the axle, so it is also rarely adjusted. Worn king pins can cause a negative camber condition (leans in at the top) that will wear the inside of the tire, but the worn parts are replaced instead of bending the axle.
Toe in is a self explanatory angle, and it is normally the only adjustment made on a coach front end alignment. It can wear the inside or outside of a tire, but not both at the same time. So if tires are wearing on both shoulders at the same time, it is either a tire construction characteristic or an overweight/underinflated condition.
Gerald