Improved web guide

A seat belt system including a web guide (150) having a support surface (192) for supporting a portion of a seat belt (30). The shape of the support surface is based upon the natural curvature of the seat belt. To determine the natural curvature of the seat belt a segment of the belt is folded to form a loop. The unstressed shape of this looped portion of the seat belt is defined by and corresponds to the natural curvature of the seat belt. The support surface, in one embodiment, is realized by a circular cylinder of radius that is circumscribed within the loop.