[João Dias]

Pretty sure I've figured it out. Here's what you do!

• Find the file path for the helmet listed in the skin.ini for the car skin you are wanting to change the helmet on. In this example, the line is "HELMET=\helmet_1969\beige1" so the full path is going to be: "[yourSteamPath]\Steam\steamapps\common\assettocorsa\content\texture\driver_helmet\HELMET_1969\beige1
  
• Determine the number of directories to go backwards so that you can get to the "cars" directory structure. In this case you have to go back through "driver_helmet", "texture", and "content". So 3.
  
• Edit the skin.ini such that in the HELMET= value, you put "..\" for each folder you need to "go back" on. So "..\..\..\"
  
• Then put the rest of the path needed to get back down to your custom skin folder. In my example it looks like this in the skin.ini file for the Lotus_25:
  

HELMET=..\..\..\cars\ks_lotus_25\skins\russell_sobie

Hey Russel, i dont know if you missed that, but I tried something like this before as I mentioned here:

...My Skin.ini being like this:

[driver_60]
SUIT=\plain\orange
GLOVES=\classicpastel\yellow
HELMET=\helmet_1969\joao          <<---- this is the folder path inside textures with my purple helmet file created from the kunos' helmet_1969.dds itself and also called "HELMET_1969.dds", but in a new folder as follows (E:\Program Files (x86)\Steam\steamapps\common\assettocorsa\content\texture\driver_helmet\HELMET_1969\joao)

[CREW]
SUIT=\type1\green_white
HELMET=\yellow
BRAND=\lotus_classic

It didnt worked by the time,
BUT, my skin was already with 9.73 mb because I placed the helmet file inside the skin folder thinking it would be uploaded from there. Maybe the SRS app was trying to download the file from textures helmet folder (in which I've placed my helmet there too) but as my skin folder was 9.73 mb and the file itself was 615 kb it exceeded the 10Mb limit.
I excluded the helmet from the skin folder to see if the SRS app downloads it from the textures helmet folder, gonna check it on next session..


But right now I've changed the helmet inside textures folder from the Audi TT Cup, the skin.ini staying the same but a new helmet file, just like updating your skin, and the Skin APP did not redownloaded my skin with the new helmet placed only inside textures helmet folder...

edit: and the new helmet works inside my game just fine!