Jeff C, I believe that explorers still use 5 on 4.5" rims. I'm not familiar with the Navigator, but I think they are the same. Explorer rims do fit sport tracs. It's the new f150 class vehicle that has a different bolt pattern.
New Explorer wheels DO FIT on the ST - bolt pattern-wise, but the offset is different. I have 17" Explorer rims on mine - with 1-1/2" spacers on the front and 2" on the back.
And, AFAIK, the Aviator is just a fancy version of the Explorer.