Cancelled 6 and 8 Lug Rim Expansion

Intro:
This is my first post here, but I've been lurking for about a year and have been playing BeamNG for month or two longer than that. I've made some mods for other games in the past so I'm familiar with the common mistake of starting with something advanced (which is usually followed by frustration and giving up). With that in mind, and knowing that BeamNG isn't exceedingly easy to make decent mods for, I'd like to get my feet wet with some simple retextures of existing assets. Eventually I'd like to put some new models into the game (I know my way around 3DS reasonably well), but I'd like to take things one step at a time.

I usually play with the cars in the game more, but when I do pull out the light trucks I've always found the selection of 6/8-lug rims kind of lacking, and no mods have seemed to work to remedy it. In addition, seeing as version 9.0 gave the D-Series some love I thought it was time to expand upon the rim selection available to the Roamer/D/H-Series. I actually started working on this a month ago, but I hit a road block with the modding end of things and set it aside for a bit. The tutorials I found didn't help much since they seemed to be geared towards more advanced modding. 9.0 renewed my interest in the idea so I decided to finish up what I had done on the 8-lug rims and present it here to get feedback and help with what I was messing up.

tl;dr - Hi I'm new here. I usually play with the cars but decided the light trucks need some more rims.

What's done so far:
So far I have 4 different textures for the 8-lug 16x8 dually rims. Nothing impressive but it's a start I guess. I've made:

Alloy


Chromed They look similar to the alloy rims but if you look closely they are shinier like the bumper and the reflection is sharper


Base/Work Vehicle


Black I'm not all that big on lifted off-roading trucks but I've seen that all-black parts are popular for it so I figured it made sense


Beyond that I'm out of ideas for the dually rims. If there's any more ideas on that front I'd be happy to hear them. Next I'm looking at the 6-lug 16x8 steel rims. They could probably come in white/grey/dirty...

Things I need help with:
First off I just have a question about one of the texture files. I tried searching for the answer but couldn't find anything. How do you open the xx_n.dds files? I edited the xx_s.dds and xx_d.dds textures in Photoshop to make these but paint.net gives me an error when I try to open the other one.

The major problem I'm having (game loads the map with no car and I can't do anything) happens when I try to make these rims into standalone parts that I can select like any other rim. As it stands I took these screenshots by replacing the default white textures for these rims in the main files. When I copied the jbeam file from the official rims and changed what appeared to be needed (names and a few other things), I realized I didn't know how to:

• set up the folder/file structure in the zip file the mod would be packaged in
• where to put the jbeams and the .dds textures I had made in that file structure
• how to make the rims know to reference those textures (I assume it's in the jbeam?)

I understand the jbeam files to an extent and have changed the values I wanted to change, but the texture part stumped me. Any help and feedback in general would be greatly appreciated.

Also, I'm happy to finally become part of this community.