Sticky Tires with White Lettering

The reason you don't see lettered tires much in modern, low profile radial tires is because it requires the addition of 2 more layers of rubber to do it. This makes the side wall stiffer and the tire generates more heat. A lettered tire is made the same as a white wall tire. A strip of white rubber around the entire sidewall. This is the covered with a thin layer of black rubber. Afterwards the tire is "buffed" lightly to expose the white rubber.
Real race tires are stenciled like the Hoosier.