This may sound crazy, but i just mounted a 19x6x10 holeshot front on a set of 10x8rims.... one mounted up fine, the other i could not get to seat myself, so i went to a tire place and paid $5 for them to seat it, but then it still leaked out of a bead....so i went to meijer(or walmart) and got stop leak in an aersol can, filled that sucker up with the whole 16oz can, then used compressor to put it at like 30lbs, still had a slight leak out of the same spot...now heres where i get inventive..
I grabbed a propane torch, heated that area of the tire up, and bada-bing! hasnt leaked since. Cant even tell i used heat.