Our Texture Bites files are 4000 pixels on the long dimension. You should always work on your images at their capture size or larger. If you need to, you can scale the Texture Bite file to the dimension of your image using the File Size command in Photoshop or a similar Transform command in whichever software your are using. Textures are very forgiving when it comes to scaling them up or down.
Just remember not to save the transformed Texture Bites file over the original file. It's best to work with a duplicate file and name it differently so that you don't change the original.