What Is Hydroplaning?
Put simply, hydroplaning is when a wedge of water lifts a tire from the road surface, causing a loss of traction. If this happens to all four tires, the driver can lose control of the vehicle and crash.
What Contributes to Hydroplaning?
Hydroplaning is caused by a combination of speed, road conditions and tire design and condition. Let’s take a deeper look at all of them:
1. Vehicle Speed
Vehicle speed is a major contributor to hydroplaning. The tire’s tread needs time to evacuate water from under the contact area (called the footprint), and the higher the speed, the less time is available for that to happen. A wedge of water can start building up at the footprint’s leading edge, growing in depth and length until the tread loses contact with the road surface. Depending on the condition of the tires, their design and the amount of water on the road, hydroplaning can occur at speeds as low as 45mph.
2. Water Depth/Road Conditions
As water depths on the road surface increase to more than 1/10th of an inch, the risk of hydroplaning grows exponentially. The intensity of the rainfall and type of road surface (for example, asphalt vs. unpaved or a gradated surface vs. flat roadway) both play a substantial role in creating hazardous conditions. Since it’s difficult to determine how much water might be standing on the specific road surface you are driving on, a good rule of thumb is to always slow down in rainy weather.
3. Tire Width & Hydroplaning
All else being equal, a tire with a wider tread facing the direction of travel will hydroplane sooner than one which is narrower. The wider footprint has more surface area to form the wedge of water at its leading edge that leads to hydroplaning. However, when it comes to tire design, all things are seldom equal. Bridgestone engineers design tires that optimize the footprint to distribute weight evenly across the tread to maximize contact with the road. And they put a lot of effort into making the most of each tread’s water channels to rapidly evacuate water from under the footprint. These two features combine to help reduce the risk of hydroplaning. Tires with optimized footprint technology include Bridgestone’s DriveGuard, and Dueler H/T 685 along with many other Bridgestone tires.
4. Tread Design and Depth
Your tire’s tread makes contact with the road surface, much like the shoes you wear make contact with the surfaces you walk on. And just like the various shoes you wear, some tire treads are better for certain circumstances than others. The footprint size and shape of various tires can vary a lot, depending on the priorities of the vehicle and its owner. Touring tires, which emphasize ride comfort and all season traction, tend to have long, narrow footprints. Performance tires, with their focus on extreme levels of cornering, braking and accelerating traction, usually have short, wide footprints. Tire makers attempt to overcome each design’s inherent limitations, but all things being equal the tire with a long, narrow footprint will have an advantage in resisting hydroplaning. Its longer footprint allows the tire more time to evacuate water. And, its narrow shape tends to “slice through” deep puddles, reducing the amount of water the tread must pump out of the footprint area. A shorter, wider footprint on the other hand, offers the tread less time to evacuate water, so engineers often compensate by increasing the size and number of water channels.
5. Vehicle Weight
If we compare two vehicles equipped with the same size and type of tire, the heavier vehicle will have an advantage in resisting hydroplaning. The reason is simple – with more pounds per square inch pressing the tire footprint against the road, there’s greater force to displace water from under the tire’s footprint. An extreme example of this is a loaded tractor-trailer; high weight combined with tires that have long, narrow (relatively small) footprints provide them with hydroplaning resistance that’s better than most passenger vehicles. However, even tractor-trailers will experience hydroplaning if their speed is high enough or their tires are heavily worn.
6. Tread Depth
Of all the factors which contribute to hydroplaning (or to resisting it) the tire’s tread depth is among the most critical. Even high quality tires will have little resistance to hydroplaning when worn to 2/32” or less, so it is vital that worn tires are replaced promptly.
How Can I Prevent Hydroplaning?
As stated before, perhaps the best way to prevent hydroplaning is to slow down when weather and road conditions become hazardous. If it’s safe to decrease your speed to 45 mph or less, do that. Yet there are still more steps you can take to keep yourself as safe as possible if you do find yourself out braving rainy roadways:
● Visually inspect your tires at least once a month and make sure that your tires aren’t worn out – that is, a tread depth of 2/32” or less. You may have heard of the quick, easy way to check – just take a penny and place it in one of the tire’s grooves with Lincoln’s head facing the base of the groove. If the tread doesn’t cover any part of his head, the tire is at or below 2/32” depth and must be replaced.
● Be certain to rotate your tires regularly.
● Don’t rely on cruise control in inclement weather. You need to be paying close attention to the road, and keeping manual control of your speed can help.
● When it rains, you should increase the distance between yourself and other traffic. And be especially alert for any vehicles ahead of yours driving irregularly; this could be a sign of areas of standing water.
● If drivers ahead of you are creating tracks on the road, try to keep your own tires aligned in them.
What Should I do if my Vehicle Is Hydroplaning?
Even if you take every precaution, there’s a chance that you can still find yourself hydroplaning. What should you do?
● First off, keep a clear head and try not to panic. Overreacting will cause the situation to become worse.
● Your first instinct may be to jam on the brakes. Don’t. Instead, take your foot off the accelerator and allow your vehicle to slow down. If you need to, and your vehicle has anti-lock brakes, you can lightly pump the brake (tap the brake and release) to help your tires regain traction.
● Hold the steering wheel steady and avoid making big steering inputs. Large movements of the steering wheel while hydroplaning could result in the car spinning out of control.
● After you’ve regained control, avoid coming to a full stop on the roadway. If you need a few moments to regain your composure, be sure to pull safely onto the shoulder or off the road entirely, if possible – remember, approaching vehicles may be experiencing the same difficulty with control that you did. While hydroplaning can be quite scary for drivers, always keep in mind that with some preparation and safety-first driving techniques, you are at far less of a risk of having it happen to you.