I imagine we need close to white to differentiate colours, see this video for more information on that.
However, the LED lights are way too bright, usually when I see an incandescent headlight its fine, but the LED ones are so bright and I have no idea why that is. I have a recollection of reading somewhere that headlight brightness is based on a unit based on a wavelength of light closer to orange, so the more blue a light is, the brighter it needs to be, but I can't remember for sure.