Also, 4k is 4096. Game textures need to be powers of two. http://wiki.polycount.com/wiki/PowerOfTwo This might be good reading for you... http://wiki.polycount.com/wiki/Texturing
Just posted this on another topic, might help you. http://wiki.polycount.com/wiki/Texture_atlas#Tutorials To understand the workflow a bit more, see http://wiki.polycount.com/wiki/Modular_environments Also in particular this might interest you. It's a bit beyond PS1 spec, but the breakdowns should be helpful…