The cast iron 4 spoke wheel was introduced on the E27N Major in 1945, and was used throughout the Diesel Major until 1958 when the Power was introduced = 6.00x19 size
Note the first Powers were fitted with 4 spoke until supplies ran out, then all Powers & Supers [blue & orange] from 1958 to 1963 fitted with 3 spoke = 6.00x19
Pressed steel front wheels = 7.50x16 were optional
When the New Performance Super Major [blue & grey] was launched in 1964 the pressed steel fronts were standard fitment 7.50x16
I believe that all export Majors were supplied with pressed steel fronts