Right you are! Found them. But I was wrong. They're 20s. Thanks for the help.
http://cgi.ebay.com/ebaymotors/NEW-OEM-Factory-20-INCH-Ford-FLEX-LIMITED-WHEELS-TIRES-_W0QQcmdZViewItemQQhashZitem27b424b882QQitemZ170526029954QQptZMotorsQ5fCarQ5fTruckQ5fPartsQ5fAccessories