John..
         I'm still surprised! We have been designing 12-14 layer (standard)
   smt designs for about a zillion years, maybe not quite a zillion, but
   a looonnng time and no vendor has ever requested that the inner layer
   pads be larger. In fact, unless I am looking at the formula/chart in
  the Mil and IPC specs incorrectly, the minimum annular ring requirement
  for internal is .001/.002 mils vs .002/.004 mils for external layers.
  Therefore, by definition, your external pads should be larger. What
  am I missing???
                                       Regards,
                                                  Bob