15 x 7 rallye wheels

HOW DO I TELL THE CORRECT YEAR ON THE RALLYE RIMS.....I HAVE 4-15 X 7's AND I MAY SELL THEM BUT I'M NOT SURE HOW TO TELL WHEN THEY WERE PRODUCED.....I DO NOT HAVE ANY CENTERS OR BEAUTY RINGS JUST THE BARE RIMS......THANKS WEBBY.