The permissible static bending stress is used to calculate the permissible static radial load and a safety factor for the bending stresses in the outer ring. The stress is calculated as maximal value of bending stress plus tension in the outer ring.
If not defined manually the software automatically selects the point of input geometry which leads to the highest stress. Only points in the geometry list are considered, no intermediate values. This could make a difference for convex radii.