My response must first start with a question. In 1936 there was technically no 4.5" wide truck rim made. So we need to know how you've measured your rim width. The standard of measurement back then, according to period National Wheel and Rim Association (NWRA) catalogs, was to measure across the rim lips. In 1936 Chevy listed wheels that were 20" x 5", and 20" x 6". These rims, however, when measured using the revised NWRA standard that came into use in the 1940s measure 3.75" and 4.33" respectively. This measurement is taken across the inner rim base. I have Goodyear charts from the era that show a 5.50" tire would be correct for a 5"(3.75") rim, but would not be correct for a 6" (4.33") rim. They show the correct tire to be either a 7.00" or 7.50" on the 6" (4.33") rim. I know I have later references that show use of a 6.50" tire on the 4.33" rim, but don't recall any showing use of the 6.00" tire (much less 5.50") on that rim.
Edit - I found a 1944 Budd reference that shows use of the 6.00" tire on the 4.33" rim. Stu McMillan
Stu, you are correct my referring to a 4.5" rim is in reference to the inside dimension, the outside dimension across the outside lips of the rim is 5 7/16"
I appreciate your input... I think I need to do more research.
