The ornamental design for a steeringwheel boss, as shown and described.
FIG. 1 is a perspective view of a steering wheel boss in accordance with the present design; and,
FIG. 2 is a front view thereof.
The broken lines shown in the drawings illustrate portions of the steering wheel boss that form no part of claimed design. the broken lines shown along the interior edge of the steering wheel boss represent boundaries for claimed surfaces.