I have been gradually building a library of high quality PBR tiling materials within Unreal Engine 4. I create these using the latest methods of PBR rendering and through the use of Substances. They are all very flexible thanks to the exposed parameters allowing to make changes in colour, roughness, normal intensity and wetness in real-time. They also utilize height based masking and vertex painting to seamlessly bend with any other materials.
Substance Designer, Zbrush, Photoshop, Unreal 4