Originally Posted by GAMEOVER
i understand but grinding the little porosity holes away might last long than paint
Um, no, the porosity is an attribute of the material; it goes throughout the metal. Painting a sealing coat of paint on the inner surface will block air penetration at the surface.
I... dunno. I would ask a couple of tire specialists what they think. If nothing else, keep in mind that a rotating tire is going to fling the fix-a-flat fluid _outwards_ against the inner surfaces of the tire, rather than against the rim. If you want to do some work on the inner rim surfaces, you're going to have to remove the tire.
I have to run a leaky tire over to the local place in a week or so; I'll ask around when I get there.