If they have a good paint matcher they can show you a couple of looks for the helmet.
The one many would like to make is a silvery gray look, that means it will need some aluminum flake or similar metallic or mica effect pigment in the paint. The other look is the gray that is used on the grill, which is actually a little darker in shade than the helmet silver-gray. Frankly Home Depot might have this, but I am not sure that is the best place to go. An even better bet is an auto-paint store, they will also have the color-matching POS machine to help you.
A good picture to print out for them to use for matching might be at this
address - its quite large!
Note that there are actually five color fields and effects to reproduce.
The white stripe, the black gloss banding, the center red stripe, the gray grille and the deep and shimmering field of silver-gray on the helmet itself. The two grays are different in shade, and there is no effect pigment in the grille gray paint.
Anyway, print in hand the color-matcher will have an easy time with the red, the white, the black and (if at an auto-store) the effect gray paint. Here is how you make that deep glossy look on the helmet.
You need a matte base coat, gray, very light is perfect. Next spray on your first "gloss" coat of the effect pigment paint (also tinted slivery gray). Let that dry. Then spray on a couple of laquer coats of untinted clear finish as a "gel-look" cover coat. Let dry. Voila, your metallic silver-gray helmet. Apply your banding working logically so that the last applied are mutiple fields of red to achieve the striping on top. (Use thin masking tape from a hobby or auto restoration store to cut clean lines).
Hope that helps.
