Hex #555555 or rgb(85,85,85) in RGB space is the tint of red. It has hue angle of 0.00 degrees, value = 33 and saturation = 0. #555555 can be obtained by mixing 2 colors: 1 drop of white, 2 drops of black.
Nearest safe hex - #666666. Below you can see the block with #555555 color and its structure: in procentage ratio and in drops of pigments. Click "TRY" button to move #555555 to the mixer and play with it.