On smooth pavement, hydroplaning is a function of contact area, tire pressure and velocity. Relatively large areas at relatively low pressures (like car tires) will hydroplane at high speed unless there's siping to direct water away from between the road and the tire. Even with siping, excessive speed can overcome the tire design's ability to get the water out of the way. A tiny contact patch and relatively high pressures (like a bicycle tire) are virtually immune to hydroplaning regardless of tread or siping, particularly at typical bicycling speeds.