Driver's Prep - Free DMV tests

What is Hydroplaning?

Hydroplaning - illustration by Victovoi

Hydroplaning – What is it?

Hydroplaning occurs when your wheels lose traction and start riding on a layer of water.

The grooves of your tires are designed to disperse water from beneath the tire, providing high friction and traction even in when the roadway is wet. When water cannot be removed fast enough, the tires will start to ride on the water, pretty much like a surfboard or water skis.

At speeds up to 35 mph, tires with good tread will wipe the road surface the way a windshield wiper cleans the windshield. As speed increases, the risk of hydroplaning increases. The risk of aquaplaning also increases with the amount of water on the highway and the vehicles sensitivity to water depth. At 50 – 60 mph the tires may lose all contact with the pavement.

If you are taking the written test for your permit or driver’s license, remember that worn or bald tires will hydroplane at lower speeds!

What Loss of Friction Mean

When your tires lose all contact with the pavement, you cannot brake, accelerate or turn. Your vehicle will slide until it either collides with an obstacle, or slows enough that one or more tires contact the road again and traction is regained.

How to Prevent Hydroplaning

First, always make sure your tires are in good condition. As a tire wears, its tread grooves become shallower, which reduces the amount of water that can be channeled through them. Check tire tread on a regular basis. Place a penny into several tread grooves across your tire. If part of Lincoln’s head is covered by the tread, you have more than 4/32 inches of tread depth remaining. If not, it is time to get new tires.

Do this well before the tread depth reaches 1/16 (2/32), which is the legal limit in most states.

Penny test - photo by Mark Herreid

Keeping your tires properly inflated also helps. Check them at least once a month. Under-inflated tires hydroplane much easier at lower speeds.

If you encounter water on the road or partial hydroplaning, immediately reduce the speed of the vehicle. Don’t drive through standing water or puddles at high speed.

In short:

  • Check tire depth.
  • Check tire pressure.
  • Slow down.
  • Avoid standing water, if possible.

More Things to Remember About Hydroplaning

Many people believe that water must be deep to cause hydroplaning. This is not true. Even a thin film of water can cause problems if you are driving too fast or your tires are in bad shape.

When your vehicle hydroplanes and has lost all traction, you cannot really control your vehicle until it has slowed down and friction is regained. Ease off the accelerator and remain calm. Trying to steer may put the car into a skid. If braking is unavoidable, do so smoothly and wait until tires grab the pavement. Be prepared for instability and a possible skid.

Try not to panic. Tires will eventually get contact with the pavement again.

Illustration: VictovoiOwn work, CC BY-SA 3.0

Penny test – photo by Mark Herreid

About Mark
Problem solver. Entrepreneur. Music nerd. Traveler. Twitter: @markheart0 Facebook: Mark Heart


  1. Good article and advice. You might want to add that you should not use your speed control when it is raining. If water has accumulated on the road, the vehicle may hydroplane when the tires encounter the water because the driver has no control over the device at the time of the water contact and the speed control device has no safety measure for an automatic turn off. The result of this encounter causes the vehicle to accelerate with the driver losing control when traction is regained because of the accelerated speed. I don’t think that braking during this event automatically turns off the speed control device, but I am not sure.

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