Hmmm. Have you managed to save a skin from the internet and got it to work without it turning muddy/stretched?
Anyway, try this:
http://www.lfsforum.net/attach ... d=107320&d=1279967028
That's a skin I've made a while back. Click on the link above, right click on the image and save it as "XRT_MMC EVO TOMMI.jpg" your /LFS/data/skins folder.
Now, in LFS, go to the pits, select the XRT and click on "new colours". The file "MMC EVO TOMMI" will appear on the list and you will be able to click on it to use it from now one.
Does that skin appear fine in-game? Or does it still looks weird?
You can take a screenshot in-game by pressing CTRL+s. The screenshot will be saved in the /LFS/data/shots folder. You can attach that image here so that we will be able to view it...
Have a go and let us know...