The majority of my textures {placed in Detail Texture} creates a very unsightly distortion, & For the life of me, I cannot find a fix or logical explanation. I can only draw the conclusion that it's down to the size of the texture giving it this stretched appearance - however! having said that, there are one or two textures that don't give me a distortion, & are both the same file type & size {working with all default textures right now, trying to resolve this, so it's not a custom file issue}

I do plan on eventually creating custom road textures for CAW, so I'm going to need to understand what is causing this problem, before I get into something more advanced.

What size & file type should the Detail Texture be? & just... what is causing this to happen?

The road texture goes into "Base", not "Detail". Detail is just for stripes or dirt overlay, it's a very short texture that will be repeated over and over again and causes the distortion you show if you use a standard texture for it. All file types should be .dds (normal maps are often .tga). See attached screenshot for what goes where for the EA dirt road.

Base Texture: size at least 512x512, DXT5, with mipmaps and alpha
Detail: size 1042x32, DXT5, with mipmaps and alpha

Go to your Source textures folder of your CAW user data folder and find the textures there. You can then examine size etc. yourself.

Here is an overview how to create custom roads in CAW: http://krrank.blogspot.co.uk/2011/1...rial-roads.html