The ornamental design for a surfaceconfiguration of a rollover bar for a vehicle, as shown and described.
FIG. 1 is a rear view of a surface configuration of a rollover bar for a vehicle according to my novel design;
FIG. 2 is a rear perspective view of the surface configuration of a rollover bar for a vehicle according to my novel design;
FIG. 3 is a front perspective view of the surface configuration of a rollover bar for a vehicle according to my novel design; and,
FIG. 4 is a elevated side view of the surface configuration of a rollover bar for a vehicle according to my novel design.
The broken lines are for illustrative purposes only and form no part of the claimed design. Also enclosed is a set of photographs of an embodiment of the design.