I want to make some rims based off of these ADV1s: However, I have no Blender skills and will only be able to work on this during most weekends and school breaks. I just want to know the basics of making these. Also, I would've asked for someone to make them but I know people don't like being asked to make stuff that much or at least not without pay (which I can't do). --- Post updated --- Also, I know I should probably do skins first, but I have no ideas for skins that don't already exist in some way, are too basic or simple, or are too complicated.
You should probably do skins first. It will get you the basic understanding for some of the file structure, so it is better to start off with that. I don't see how it matters that the skin is already made, or is too simple. It is not like you have to release it or anything, it's just to try to actually do some modification first before standing off modeling. You could also just try to do something like a box first, and learn how to create and export something simple into the game. (not sure if this is outdated, tutorial by Nadeox1)
That is not for car parts, static objects are for maps and have different steps to follow. D-troxx has a tutorial on a discord server for a 3-piece model but yours should be made with an array. This video works as well: To get it ingame you need to make textures and a jbeam(physics model). You can copy another wheel's jbeam and rename things for your model and wheel and finetune it for the desired properties.
As I wrote; I am aware that it is not for car parts. If you have 0 blender experience then it is surely a good idea to start off with learning the basics of modelling in the software and how to export it.