The ornamental design for a spoke wheel, as shown and described.
FIG. 1 is a perspective view of a spoke wheel showing my new design;
FIG. 2 is a top plan view thereof;
FIG. 3 is a bottom plan view thereof;
FIG. 4 is a front elevation view thereof;
FIG. 5 is an isolated view on an enlarged scale taken from FIG. 4;
FIG. 6 is a rear view thereof;
FIG. 7 is a left side elevation view thereof; and,
FIG. 8 is a right side elevation view thereof.
In the drawings, the dash-dot-dot lines represent portions of spoke wheel that form no part of the claimed design. The dashed broken lines define the boundary of the claimed design and form no part of the claimed design.