both parties have their extremes, and by that definition they have radicals in their party.
we can go down issue by issue which party has extremes on which issue, but at the end of the day we are not even arguing the overall prevalence of fringe elements on each side of the aisle, we are arguing the extent to which these elements are accepted. a problem arises when we attribute radicals to a party, when the party has been rejecting the platform of the radicals.
take Sandy Hook, this has gotten brought up by Alex Jones, who is nominally right in many areas, but when he brought the idea of Sandy Hook as a conspiracy to Megyn Kelly's show, he gets ridiculed by her, and the reaction by the mainstream right agrees.
the mainstream left has been more and more willing to accept and platform the radical far left, most notably with Bernie Sanders and the rise of socialism.
as far as the extent of the radical left and right in size and number, i do not have any statistics in front of me to say one way or another which is bigger. i think each have grown in recent years though, although that's a purely visceral belief and i could very well be wrong.
what we need to assess is the extent that radical ideology is accepted by political parties as mainstream.
and before you go bashing Trump on being radical, he's not very right wing in that he is not for free markets, he wants trade restrictions, he is willing to spend big, he seems to enjoy centralized power, he is far more socially liberal in some issues for LGBT than most Republicans.
he's a volatile person for sure, but politically he's somewhere between a centrist democrat and a neocon while governing so far.