In Japan, no matter how cold it is, girls tend to wear skirts or shorts with tights. Apparently, being fashionable requires endurance. But even within this endurance, they are very picky about the thickness of the tights they wear and how their legs look in them.
The units for representing the thickness of tights are called Denier. The generally sold denier numbers of tights are from 30 to 210.
Here are the reference images....