According to the 68 Plymouth price list code 46 is a "white streak" tire. Perhaps some confusion and/or mistakes are because on the second page, code 46 also says "replaces F70x14 red streak tire". Maybe someone missed the "replaces".

http://www.hamtramck-historical.com/imag...lvedere0005.jpg

http://www.hamtramck-historical.com/imag...lvedere0006.jpg

Just my