I have quite a few skintones that I use in my game. Each creator has several different skin tones on their websites. As long as they say non-default you can add all of them to your game. Just in case you are not aware. You can only use one default but you can use as many non-default skin tones as you like.
Comments
Navetsea
http://navetsea.blogspot.com/p/the-sims-3-skin-mods.html
SClub
http://sclub.mktm.co.uk/en/
LemonLeaf
http://blog.sina.com.cn/s/blog_63e832e00102dros.html
LadyFrontBum
http://www.ladyfrontbum.com/?category_name=genetics
Klavix
http://blog.sina.com.cn/s/blog_71be8a2d010160q0.html
http://blog.sina.com.cn/s/blog_63f63ea901011yv7.html
http://blog.sina.com.cn/s/articlelist_1677082281_1_1.html
http://mysims3blog.blogspot.com/search/label/Skin%20Tones