Well. Maybe not tiny, but with 7 1/4 inches (I’m not even going to bother the Trump with metrics, but it’s 18.1 cm) notably below average for a man of his size. And as in Trump’s world there’s only big and very tiny - there you go. (But I’m sure that’ll change very soon - with Trump’s stance towards facts, I’m sure we’ll see a new definition of the word “average” any time soon if he wins to assure they’re actually huge.)
So far there’s no information about the correlation to the size of the other body part that played such a vital role in his campaign.