On the back side of the outer ring, select every second vertex as shown and move them outwards to create bumps.
Now extrude the two inner polys on the outer ring that line up with the arm we extruded out of the center part of the steering wheel. Just extrude out a small distance like in the picture. Move the polys inwards a little so that the extrusion is at an angle.
Chamfer the edges shown in green all the was around the ring. You will have to do some vertex cleanup in a couple places to get rid of triangles. I used a chamfer setting of 0.1.
Put symmetry and meshsmooth modifiers on the outer ring and the inner ring as well. Shift-drag the cylinder you duplicated earlier and scale it down so that it fits in the hole as shown. Now use the connect tool to cut in the edges highlighted in red in the picture.