426 Hemi's can be considered the holy grail of all Mopar engines. From 1968-69, all 426 Hemi Chrysler cars came with steel wheels stamped with the "JK" code. These JK coded wheels are also correct for 1969 A12 equipped cars as well. A stamped number 839 should also appear beside the JK code.
All correct JK stamped wheels will measure to be 15x6". From the factory, these steel wheels would have come with a Polyglas Tires size F70-15.
Another trait to look for is a stamped/raised "U" between the lugs (pictured below).
It is virtually impossible to find a set of correct and original JK wheels. Often times, collectors will use different wheels to make a complete set. JK coded wheels were manufactured in the USA and also in Canada.