radials will make it seem like you do have power steering compared to the bias ply tires these trucks came with, regardless of width, and any radial will have a "wider" footprint than the bias tires because of the softer sidewalls, but still give better preformance in every respect .... same tire sizes should do fine on either 5 1/2 or 6 - I have 700R15LT on my 58 [5 1/2"], good match to original appearance

Bill


Moved over to the Passing Lane

"When we tug a single thing in nature, we find it attached to the rest of the world" ~ John Muir
"When we tug a single thing on an old truck, we find it falls off" ~ me
Some TF series details & TF heater pics