In the CMYK colour system the RAL 7043 is composed by combining four primary tones of pigment. To achieve this exclusive "traffic grey b" colour tone, out of 100% maximum colour components, 20% cyan, 5% magenta, none yellow and 80% key (black) are used.
You can immediately see this result on this computer simulated CMYK diagram.
The mixture of these primary colours blends in the middle on a square space where all four different colour hue sheets overlap.

The conversion of RAL 7043 into RGB colour space requres specific composition of red, green, and blue primary colours. To construct hue matching "traffic grey b" colour from the RAL chart as close as possible, we use the following values ranging from 0 to 255 on the RGB colour system: 79 red, 82 green and 80 blue.
The three circle RGB diagram here provides illustrative example showing how green value stands out just enough in comparison to red and blue to construct this unique tone of colour. The RAL colour equivalent emerges in the very center, where all three primary colour circles overlap and combine.