Replacing landscape textures

[lazylizard]

Greetings. I've recently begun experimenting with changing the landscape textures in the game, but I haven't gotten it to work. I read up on the .blp format the game uses, which seems similar to the .dds format most other games use. I started by creating higher resolution textures for Durotar which is found in the Tileset folder. DurotarRoad.blp is the one I changed first as a proof of concept. I converted the new textures to .blp using the BLP2 format just like the original textures did, and I made sure DurotarRoad_s.blp had an alpha layer. Then I placed the new files in Data/Tileset/Durotar in my WoW folder which is the same folder structure as the original ones. The new textures refuse to appear ingame though. I assume the loose files should override the packed ones in the .mpq, since this method works for replacing sounds.

I've tried numerous BLP converter tools but none of them seem to make a difference. I've tried having the textures in both 1024 and 512 resolution (I seem to recall reading that 1024 is the max resolution the engine supports). What am I doing wrong?