It is strange. To be honest, it is probably more like a 4% difference. My left triceps is a little bigger but my left arm has a much bigger skin fold whereas my right doesn't have much of a skin fold at all. My right arm has road map-ish vascularity and my left arm has probably 1/4 of the vascularity of my right.
If I can get a good pic that shows what I'm talking about I will post it.
Thanks for your help Marcus.