If you've had Spintires Plus in the first game (Spintires 03/03/16), or you are completely new to the game and are wondering how YouTubers, friends etc. have the Dev Tools and battery winch, you've come to the right place! This tutorial will show you how to get the mod and be able to use it as easy as possible.
SpinTiresMod is an executable program. Meaning you download and install it with the setup.
Once you have installed SpintiresMod with the setup (which I assume you know how to do. If not, ask below for guidance), it will launch. On the top left there is a button that says Mod Settings as seen in the screenshot above. Click that. Then, this window will appear.
Click the Install... button on the right under Spintires Mudrunner Directory. Another window will appear that shows all your folders and drives.
Navigate to This PC
--------LProgram Files x86
(or wherever you have Steam installed on your drive(s). In common, select Spintires Mudrunner and click Ok, then click Apply and Ok on the Mod Settings window.
Launch MudRunner from the SpinTiresMod window. In game, you will have a new button in Settings at the bottom right that will say Advanced Options. Here, you can apply the features you would like to use. Also, you must launch MudRunner from SpinTiresMod on your desktop. Any other way - through steam library - will launch the vanilla game without the mod. Similar to TruckersMP. And you're done! (this also works for Spintires 03/03/16. Just install the SpinTires directory in the according Install... button)
Disclaimer: I am not the creator of this software. Official publisher can be found here