51shad,
Radials will work on original wheels (16" or 15"). If your wheels are not pitted, you might not need inner tubes; otherwise, radial tires with inner tubes will also work fine.
The standard 6.00-16" rim has a 4" rim width; the optional 6.50-16" has a 4.5" rim width; and, the optional 15" rims have a 5" or 5.5" rim width. Some tire dealers might balk at mounting a radial on such a narrow rim (I have had no problems getting them mounted).
If you use high-profile truck (LT) radials, the high profile will not only look original, but also put less sidewards stress on the wheels (if that really matters at normal speeds and on modern roads).
Most tire manufacturers sell LT radials that can be mounted on the narrow original rims.
Tim
