i had the same problem when i bought my 40th, slight rash on the passenger rear wheel.
i went to kragen (o'reily's) and just color matched my wheel with the selection of touch up paints that they had, came down to one color and it worked!
paint code is NG FM 360 (dark shadow grey metalic CX) for a ford, costed about 7 bucks
It matches so well that it really make it difficult to find where the curb rash was. I have to take a finger and feel the edge of the rim to find it! hope this works
before, bottom right corner, the rash was about 3/4 of an inch.
after, in between the tire size and forge marking on the wheels
