That looks more like a mini-velo rather than a true folder. If I were to guess, maybe 451s in front and 24" in the rear ala the Airnimal?
Well, looking at the HED site, it appears they don't make 24" wheels. It might be 406 in front and 451s in the rear (or it could just be the camera angle)?
http://www.hedcycling.com/wheels/recumbent.php