Ok, here is what i do. first, if the burnt out section is at the tracks, then you will need to get some Panther burnt out road wheels to make it look like the rubber has burnt off. or what you could do is grind the rubber part off, or do it on one, and then make some resin copies. Painting and weathering wise: i usually paint it black, then lightly go over with a rust color, then take some orange pastels and then "blotch" in some areas to make some variation. then make a pile of ashes with black, grey and whit pastels, white accenting the brunt rubber and zimm.