[SS Tim]

Both actually. The H78/15B tires were upgrade sizes and sometimes a required option dependng on how the truck was ordered. They were available as blackwall highway and/or on/off road tread and also as white stripe highway tread tires. The RPO PV6 you have is a set of five H78/15B bias belted white stripe highway tires.

As far as I know white stripe tires were not standard on any of these trucks nor at any trim level. However there may have been "specials" that included them but not the Inflation Fighter (YF7) nor the "Highlander Package" trucks (YG6,YG7 or YG8).

BTW: Thanks for leaving the year and plant codes up.