In 1966 all wheels were 14 inch (in 1965, I-6 cylinder cars had 13 inch). The normal size was a bias ply 6.95 X 14 black wall. I-6 cars used a Rayon material as standard. Manufacturers were Firestone, Goodyear and U.S. Rubber. Options included nylon material, white side wall and dual red line side wall. If you want reproduction tires, go to http://cokertire.com/
for price, availability and sellers.