Chris,
   Let me correct myself on two things(I hit the SUBMIT button before I proofread what I wrote) .
1. The rear trailer wheel rides in the last furrow(most recent ) furrow plowed but does in fact act as a rolling landside. 
2. To clarify, I meant the rear wheel should be harder and sharper in my opinion than the front two because it is what runs in the last furrow and being sharper/harder, it holds the furrow nicer.
    It doesn't pay to rush... <!-- s:wink: --><img src="{SMILIES_PATH}/icon_wink.gif" alt=":wink:" title="Wink" /><!-- s:wink: --> 
          Cal