Average Asian size

Shoe size, height, clothing size, Penis size? That's really vague question.

Regardless, it isn't something that is easy to answer. Studies may vary based on genetics, regions, or other factors (in short, much room for error). Most data you will find might be extremely biased as well (ie. only Koreans living in America, only Chinese living in Japan, Mongolians in Vietnam..etc).

Also, you mentioned "Asians" when I think you are interested in only people of Oriental background. If you search for "Asian ___ sizes" it may include countries such as Turkey, Israel, India, so on and forth.