http://www.hpb.gov.tw/files/11-1000-129.php

※水漂（Hydroplaning）是什麼？

◎NASA（美國太空總署National Aeronautics and Space Administration（of U.S.A.））水漂臨界速度（公里/時）＝16.66×√胎壓

◎小型車輛行車速度在時速91公里（57Mile）時，就會發生水漂，不必考慮其他影響因素。

車輛行經積水區，因某些因素致使汽車輪胎與地面之間形成水膜，輪胎無法完全接觸地面，汽車因而發生打滑、失控狀況。

資料引用http://www.mountainflying.com/hydroplane.htm

※水漂的原理

◎三種造成水漂的作用力

1.動態水漂（Dynamic Hydroplaning）

是輪胎完全被舉起於路面積水的狀況，只要路面有十分之一英吋（0.25公分）的積水，並達到NASA水漂臨界速度（NASA critical speed）就會發生。

2.黏稠水漂（Viscous Hydroplaning）

在較低速度時就會發生，而不在輪胎被舉起於路面時，輪胎在薄膜上滑行（通常是含有油污或灰塵的水膜），這種狀況會發生在平坦的路面。

3.蒸汽水漂（Rubber Reversion Hydroplaning）

在行進間遇到緊急狀況時，駕駛人常會踩死剎車，如果是在濕潤路面，輪胎的胎紋部分因磨擦生熱，引致胎膠呈現黏軟狀況，並包覆著水，水會轉成蒸汽，而蒸汽壓力會將輪胎舉離路面。

※水漂現象之影響因素:

1.水深。 2.車速。3.車重。4.胎寬。5.胎紋深度。6.胎紋設計。7.胎壓。8.積水黏稠度。

※水漂現象之發生原因

1.車身過高。 2.車身不平衡。 3.胎紋不足。 4.深水區。

雨天注意事項（如何避免水漂現象）【資料來源NHTSA:National Highway Traffic Safety Administration（of U.S.A.）】

1.開車前：

(1)注意氣象報告。(2)檢查輪胎，讓輪胎保持在建議水準。(3)檢查雨刷。(4)檢查雨刷水。(5)檢查玻璃除霧裝置。

2.旅途中：

(1)檢查剎車系統。(2)減速慢行（在濕滑路面）。(3)逐漸減速（勿突然減速）。(4)避免突踩剎車或急轉。(5)打開頭燈。 (6)保持2倍之行車距離（約需200公尺）。(7)練習防護駕駛。(8)避讓他車。(9)穿越積水區特別注意（尤其是在轉彎處）。(10)預期發生水漂現象，保留對向來車之空間。(11)注意對向來車濺起水花。(12)如果不能從後視鏡分辨輪胎駛過路面之軌跡，那表示你已經算是在水面滑行了。(13)注意側風。 (14)平滑舖路易造成水漂現象。

※遇到水漂現象該如何

1.不要踩剎車減速。

2.保持車向正前方，不偏轉方向盤。

3.放開油門。

Hydroplaning: the Role Tires Play　https://www.tirerack.com/tires/tiretech/techpage.jsp?techid=16

Hydroplaning happens when one or more tires is lifted from the road by a wedge of water that gets trapped in front of and under a tire as the vehicle drives through water. Hydroplaning most frequently occurs during heavy rainstorms when water creates puddles on the highway or expressway. In addition to the accompanying splash and scaring the heck out of the driver, hydroplaning typically causes the steering wheel to jerk and the vehicle to abruptly pull towards the puddle.

The speed at which a tire hydroplanes is a function of water depth, vehicle speed, vehicle weight, tire width, tread depth and tread design. It depends on how much water has to be removed, how much weight is pressing down on the tires and how efficient the tread design is at evacuating water. While deeper water, higher speeds, lighter vehicles, wider tires, less tread depth and less efficient tread designs will cause tires to hydroplane at lower speeds; all tires will be forced to hydroplane at some speed.

As a rule, tread design affects hydroplaning resistance at high speeds and in deep water. Tread compound affects wet traction at lower speeds or in shallow water.

Directional tread designs (sometimes called Unidirectional tread designs) are frequently used on tires intended to better resist hydroplaning. Their multiple tread grooves are aligned in a repeating "V" shape to increase the tire's ability to channel water from between the tire's footprint and the road. Somewhat like the vanes of a water pump continually pushing water in one direction through the engine, the grooves of a directional tire are designed to push water in one direction through the tire (forward on an angle to the sides). Directional tread designs are especially helpful in increasing hydroplaning resistance when relatively wide Plus Two, Plus Three or Plus Four tire and wheel applications result in fitting a much wider tire to a vehicle than its Original Equipment size.

看來單導向輪胎（Directional tread designs），還是有它的好處！