White tires........ even the tread.

 

Yup, the natural color of rubber is a slight off white, the color we're all used to is derived from the addition of carbon black to the rubber mix. In the early days of the automobile and up into the 1910-1915 era, tires were white, but then the manufacturers like Goodyear began adding carbon black for durability. White wall tires are/were an affectation emulating the old all white tires, they just have a strip of white rubber included in the sidewall meant to be shown.

 

X 2, example: 1905 H-D