I was hoping some of you seasoned pros could give me some tips for painting realistic looking tires, something better than just an airbrushing of flat black. Anyone know of any tutorials?

I paint them a a very dark grey, drybrush with a dark grey all around, then a heavier dry brush with dark earth or a mud color around the outside contact area, then give a heavy wash of black around the hub and maybe burnt sienna or other dark brown/earthy color nearer the outside.

I also sand down the contact spot so it doesn't look like the plane is standing on it's tip-toes.