I heard the change over took place early in the 1970 model year(7.75 x 14 tire to F78 x 14 tire), Oct 69? I was questioning if the (7.35 x 14 tire- E78 x 14 tire) was used for 14" rim cars or at least intended for them? Sounds like from that early publication the 7.75 x 14 tire was for both 14" and 15" rims!