The ornamental design for a pair of middle side covers for a four-wheeled motorcycle, as shown and described.
FIG. 1 is a front right perspective view of a pair of middle side covers for a four-wheeled motorcycle;
FIG. 2 is a right side view thereof;
FIG. 3 is a left side view thereof; and,
FIG. 4 is a top plan view thereof.
The broken lines showing other portions of a four-wheeled motorcycle are included for the purpose of illustrating environment only and form no part of the claimed design.
The right middle side cover and the left middle side cover of the pair of middle side covers for a four-wheeled motorcycle are mirror images of each other.