Many thanks for the posts. Coker is charging $118 for the tires-which seems about what others are getting.
As I have someone willing to change tires this time-will stay with the 18"s.
Thanks, Jerry. Will shop for a set of 19.5" wheels as later replacements. Will add these to spare engine, etc, in barn.
Pretty soon, will be able to build another truck from spare parts being accumulated.
Thanks again to all.
Jones