Primitives in OpenSCAD are a really great for adding and subtracting your way to what you want.  Add a cylinder here, subtract another there, you got a rim.

However if you have a complex shape that can be extruded, a polygon will be much more efficient.  A little harder to visualize though for sure.

You define your profile as a set of points which define a 2D object.  Be prepared to do some math..  :)

polygon(points=[
    [rim_ir,rim_h/2-rim_edge_z-wall_thickness],
    [rim_ir+wall_thickness,rim_h/2],
    [rim_or+wall_thickness,rim_h/2],
    [rim_or+rim_edge_x,rim_h/2-rim_edge_z],
    [rim_or,rim_h/2-rim_edge_z*4],
    [rim_or,-rim_h/2+rim_edge_z*4],
    [rim_or+rim_edge_x,-rim_h/2+rim_edge_z],
    [rim_or+wall_thickness,-rim_h/2],
    [rim_ir+wall_thickness,-rim_h/2],
    [rim_ir,-rim_h/2+rim_edge_z+wall_thickness],
    [rim_ir,-hub_offset-wall_thickness*3],
    [rim_ir-wall_thickness,-hub_offset-wall_thickness],
    [rim_ir-wall_thickness,-hub_offset],
    [rim_ir,-hub_offset],
]);

Which gives you your 2D object.

Then you do your extrusion on that by adding a rotate_extrude(), and you got your 3D shape.

Add some holes, and you got a rim.  Well actually, the position of the holes defined the position of the rim above, but now I get to add them back in.  :)

The code which generates that is 20 lines long, and most of those are just for readability of the polygon array.