Method of rubber on a quater panel after a burn out?

[Len Geisler]

I want to add some more detail to my Draggen Wagen I posted the other day, and want to simulate some rubber that would gather on a quater panel after a burn out and wondered if anyone has a method of doing so they could share?

Thanks!!!

[envious8420]

yeah Dave, that beats my thick flat black thru the airbrush. Looks Real Good!!