My approach is somewhat different. I mostly build armour in scale 1:76, 1:72 or 1:48
I paint the tracks a flat dark bluish gray. (Similar to dull steel, but with no metallic pigments.) I give this a black wash to bring out details and then while the wash is still wet a sprinkle of reddish and earthen chalk-pigments. Once the wash is dry i give the trachs hard brushing. Lastly I finish it of with a light drybrushing with a mix of steel and gunmetal metallics.
If the track has rubber parts, the last session is done with black cut with a grey colour in stead.
If you don't have readily access to armour, heavy tracked engineering equipment are a good substitute to study. (Just looking at pictures isn't quite the same.)
I include two pictures.
The fist is a Köningstiger in scale 1:76
Second a KV-1 in 1:48 scale