I created a PUVtiles texture on a high poly version of a model.
Then cloned the texture, and exported it.
Now I wanted to apply the texture of the high poly model, to the low poly version of it.
In the online docs it sais to simply make a New From UV Check Texture, then import the predone texture, and apply it by loading it through the little texture icon.
Well, I did that, but it applies the texture as tiny little tiles all around the model…
what am I doing wrong? 
Thanks in advance! 
So you created UV mapping on one model, exported the texture, and are now trying to apply that texture to a different model? If my understanding is correct, then it won’t work because the second model won’t have the UV mapping that the first one has. The OBJ contains the UV mapping; the texture does not.
What you would want to do is forget mapping or creating a texture with the first model. Instead, select the second model and assign UV mapping to it. Export that model. Append it to the high res model as a SubTool and divide it to have as many polys. Now turn off Zadd (leaved Rgb on) in the Draw palette and then use Tool>SubTool>Project All to project the polypaint from the source model to the new one. You can now use Tool>Texture>New from Polypaint to create the texture, which will wrap correctly on the low resolution model.