Rex,

The Carolina tartan doesn't have the typical explanation of the colors used(red is for..., blue is for...) Instead it's based on a sample of tartan connected to King Charles, who was a Stuart. Carolina is from the latin for Charles and was named after the King. I'll direct you to the best resource out there (put together by Matt Newsome) if you're interested in the whole story:

http://www.carolinatartan.com/

Cordially,
David