I asked him about it and his reply was quite interesting. "lOOKatme" is all about making the car faster and handel better and not much about looks - although his car looks incredible to me.

Having smaller wheels brings the center of mass of wheel+tire closer to middle of the rim, which lowers the moment of inertia. The wieght and smaller radius basically lets these wheels spin faster when needed

It sounds kinda silly to put 15" wheels on a 5th gen I guess, but it turned out rather well. Maybe when I get enough money I'll think about it