It's red that leans a little towards orange in the sun. I used Mazda flame red to paint mine. Later on I switched the red paint for red vinyl. These caps started in 1969 so whatever red they used should be one of those colors?

After I buffed my hubcaps out I had a lousy time getting the paint to stick + clean and crisp lines masking by hand is rather difficult. I ended up drawing up a pattern of the shapes in AutoCAD and had a sign shop cut them out of vinyl.

The red on the cap is this photo is painted the Nissan color. I have since removed the paint and went to a generic red sign vinyl. All the satin black is vinyl and applied like a sticker.