well i want these helmets and the AI and the tyres
Well, then there are 2 options:
Have the helmets, tyres and the AI but you're unable to save your game.
Don't have the helmets, tyres and AI and you are able to save.
Only track files altered and AI altered will stop you playing online oh and surface material mods too. If it is cosmetic like skins HUD helmets all should be okay (caveat so far) the only problem with it is you only see your custom skins, in order for others to see it they must have it installed. So just replace the original AI file's when you want to go online and voila all is good (25y comp xp & 10y programming and modding xp) so my advice may not be to accurate, take it as you will.