This is a short one. How ever you make your textures I'll show you how to make it a custom pattern for Photoshop to fill it on your track

First, open your textures in Photoshop. It's not needed but it helps if you resize it to the same size of your texture map. click the image tab at the top then select image size.
From here click the edit tab at the top then define pattern. that's it! now you can fill with this pattern.