to finaly answer your question :
the black circle is a part of
StadiumRoadDetailsD(I have put a pink color on it)
it's the big circle in down-left-corner of the image.dds
TheSkid marks can't be put in a mod but for only your own game.
It's inside
C:\Program Files\TmNationsForever\GameData\Vehicles\Media\Texture\ImageThe file are:
*
AsphaltMarks.dds and
AsphaltSmoke.dds For skid mark on road (as showen in your pic)
*
DirtMarks.dds and DirtSmoke.dds (for the skid mark on dirt)
but as i said ive already try in a mod an did'nt change.
But you can edit it for your own game
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(don't forget backups)
A trick to your next search of fabrics....
Do what i did: open all textures from
C:\Program Files\TmNationsForever\GameData\Stadium\Media\Texture\Image in your photoshop or photo editor and watch them
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note them, that'S what i did to learn
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Sorry but the first time (and im french speaking) i did'nt understand skid mark, that's why i tought you were talking about the base textures
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Hope it help this time
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****EDIT****
I just did the "how to"
video tuto here :