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.