Rat Bikes! Pub Bikes Beaters! Frankenbikes!

My Retaard bike in CX-competition setup
Tires: Front 28c cx-tires, 25c road rear
Drop: Nitto 36cm B123 angled in poor-mans-hoods surrogat
Brake: Tektro mounted to be reachable in the hood surrogat
Wheels: Rear 36h custom(uuuhhh)powdercoated Bolt-on-shizzle
Front: Powdercoated with BMX-hub (10mm axel) laced on 36h rim (weighs in at 1.5kg in 28c setup :))
Frame: MaxWay aka. plumbers nightmare
Ride experience: Soft as butter without any feeling of feedback or control

Why did you choose to have a larger tyre on the rear?