Every time I pull the rear wheel, I clean and re-grease the toothed drive hub and the drive from the bevel box with Bel-Ray Waterproof Grease. Liberally, I might add. Copiously, even.
It appears that I am likely over-greasing and the excess makes its way to my wheel (and tire ) eventually.
(Having struggled to achieve a sealed rear drive, this splatter does not smell, at all, like gearoil. Pretty sure this is grease.)