The ornamental design for a wheel tread, as shown and described.
FIG. 1 is a perspective view of a wheel tread showing our new design, it being understood that the tread pattern repeats circumferentially throughout the outer circumference and shoulder of the wheel, the opposite side perspective being identical thereto;
FIG. 2 is a front elevation view thereof; and,
FIG. 3 is a side elevation view of the right side thereof, the left side elevation being identical thereto.
In the drawings, the broken lines are for the purpose of illustrating portions of a wheel tread that form no part of the claim.