Someone was wondering how I made my textures. I hope you find it useful too!
The epic texture tutorial! 
Usually I make sure I have the model completely finished before I start anything.
Then I UV unwrap the object. For this I did NOT put similar UV islands over each other to save space, instead everything has its own pixels for maximum variation.
After that I bake the ambient occlusion so I can get a good idea where to put the dirt/scratches. This is way more helpful then saving the UV coordinates as an image.

Then I start on the super fun part, texturing!
For texturing, this is really the ONLY spot you can give an object a story. When coming upwith the texture keep these things in mind:
Where has it been?
How was it used?
How well was it taken care of?
How long has it been used?
For the wheels:
Where has it been?
Through a bit of mud,rocks, now traveling over super soft dust.
How was it used?
To pull a heavy vehicle over hard objects at race pace.
How well was it taken care of?
It’s been beat up but constantly serviced (this explains the dark dirt/grease and scratches on the bolts)
How long has it been used?
For a while, this is a low budget off road rig 
Of course while you are texturing you can keep adding to this list.
Also get a ton of references. The more you get, the more realistic it will be :).
When I am doing the scratches, I have two different work flows I use on the same texture.
I made a Photoshop scratch brush that is pretty thick with a bit of scattering and a lot of size variation. (I will attach a picture of the settings later, I am on a different computer at the moment). With that, I trace around all the edges that would get scratched constantly. It will look really even at this point.
I temporarily removed the ambient occlusion layer for all the images so you can see the texturing details better.
