How do I make custom terrain materials to do the following: - Be like mud or sand where wheels sink into the ground, and, - Enable or disable tire skid marks. I am not sure how this is supposed to work, as duplicating pre-existing materials and changing the name causes them to not be recognised as such a material. See below in the image, where I copied the original dirt and made my own version under a different name. Now it does not act like dirt, but asphalt, as you can create skid marks and all that. The dirt next to it that uses the original dirt namespace "RockyDirt" is fine, and you can see that the skid marks stop at the boundaries between the copied and original material.