I would like to start out by establishing my expertise. I was a driving instructor at one of two Emergency Vehicle Operations Centers in the United States. The Center was on seventy-six acres of land with a two and one half mile high speed banked track and a very large polished concrete skidpan. There were also lanes and traffic lights set up to measure reaction and perception time and a large paved area to teach slow speed driving. I taught slow speed, high speed and Code 3 driving to Police Officers, Fire Fighters, and Ambulance Drivers. I also taught teen and adult classes. I had to go through both driving and teaching classes to be certified as an instructor in the different aspects of driving I was going to teach. Before that I spent 25 years as a law enforcement officer in Southern California, 17 of those years driving a marked police car. I drove in a lot of high speed pursuits in all kinds of weather.

First lets talk about Hydroplaning and what causes it. Hydroplaning is what causes accidents in the rain. When driving on a wet road your tires squeegee the water off the road. The water is diverted from under the tire through the groves in the tire, the tread. When the tread is worn away the water has no place to go. Believe it or not, the road is dry on the small patch of road your tire has contact with. When water gets in-between your tire and the road it is called Hydroplaning. You do not have any control when your car is Hydroplaning. You can turn the steering wheel all you want and your car will continue in a straight line. That is not going help when you enter that curve ahead. The back end of your car is free to slide in either direction. Worn tires, low tire pressure and driving too fast in the rain causes hydroplaning.

Now let’s talk about speed. Well, how fast is too fast. Your first indication will be when you start loosing your ability to steer. When this happens, take your foot off the gas and “Do Not Touch the Brake.” If you touch the brake, the back end of your car will start to come around and you will be in a skid. Have you ever noticed that when you put on your brakes the front end of the car goes down and the rear of the car goes up. This is because weight transfers when you’re braking to the front of the car. Weight is shifted off the back wheels and onto the front wheels. The back tires start to skid because there is less weight holding them down to the road when you apply the brakes. If your back tires do start to skid you turn the steering wheel in the direction of the skid and lift your foot off the gas pedal. Remember, “Do Not Touch the Brake.” What direction is that you say? It is the direction the back end of your car is going. If the back of your car is sliding to the right you have to turn your steering wheel to the right. If back end is sliding to the left you turn your steering wheel to the left. You have to do this quickly and just enough to stop the skid. Usually what happens is you over correct and start skidding in the other direction. Don’t worry, this skid will usually be much smaller and can be controlled just like the first one because you are slowing down. Remember, your foot is off the gas and the brake.

You can drive much faster in the rain without hydroplaning if your tires have the right amount of air in them. Proper tire pressure is very important. The tire companies have done a lot of research into the effect of tire pressure on hydroplaning. The bottom line is that if your tires are under inflated, you will hydroplane at a much lower speed. The U.S. Air Force did a study on the effect of having just one under inflated tire on a trailer that you are towing. They concluded that in the rain the trailers flip over much more easily if one tire is under inflated.

There are wear bars cast into the rubber of your tires tread. If you don’t put on new tires before the tread is worn down to these wear bars, the water under your tire will have no place to go and you will hydroplane in the rain.

Let’s get down to driving in the real world. When you are driving in the rain and you are approaching a curve, let up on the gas pedal and if you still need to reduce your speed, apply the brake gently. If the road curves to the right, before you approach the curve move to the left or high side of the curve. As you start to enter the curve drift down to the apex, the low side of the curve.. Let up on the brake before you turn the steering wheel as you enter the curve. Remember, the front of your car went down and took some weight off the rear wheels when you applied the brakes. You want to take your foot off the brake pedal and let the car become level again before you enter the curve or the back end of the car will have a tendency to slide because there is less weight on the rear tires. If the back of your car does start to slide, it will slide to the left and you will have to steer left to stop the skid. That’s why you entered the curve near the apex or low side. You gave yourself some room to correct to the left without going into the oncoming lane or off the road. This is what race car drivers do so they can enter turns faster. It is called entering the turn low and coming out high. Practice this in your daily driving. Say “High, Low, High,” as you enter curves on the high side, drift down to the apex, the low side and exit the curve into the high side. But remember, all this has to happen in your lane.

Now let us talk about the front wheels a minute. It’s raining and you’ve entered the curve low near the apex. Your foot is off the gas pedal and you start turning the steering wheel but the front tires are skidding and you are not turning causing you to continue in a straight line. If you hit the brakes you are just going to spin in circles. If you turn the wheel more you are going to continue sliding straight ahead and into the oncoming lane of traffic. You entered that turn low in order to give yourself some room to maneuver without crossing into the oncoming lane. Do Not Hit the Brakes. Back off on your turn (reduce the angle of your turn) until your front tires start biting into the road again and as you slow you will regain control.

Remember, tire pressure, tread depth, and speed. If it turns out your going to fast anyway, turn into that skid. Well, that’s probably more than you wanted to know about driving in the rain. Be safe.