look like STANDARD 14" black wall tire originally:

RH23 = Satellite hardtop
21 = 225 /6 1bbl
5 = auto transmission
31 = 7.35 x 14 black wall tires
501 = "SCHEDULED" 5/1/68
316539 = shipping order #

1 of ~2,421 /6 auto '68 Satellite hardtops