How to Avoid Hydroplaning in Broward's Afternoon Storms

The 4 p.m. storm, explained by the calendar

If you commute in Broward, you know the pattern: a clear morning, clouds building through the afternoon, and a downpour right as everyone gets on I-595.

That isn't bad luck. It's the season. The National Weather Service office in Miami defines South Florida's rainy season as May 15 to October 15, the stretch when 60 to 70 percent of the year's average rainfall arrives, with showers and thunderstorms developing almost every day.

NWS Miami also notes that June is usually the wettest month, followed by September and August. The calendar end date doesn't switch the rain off. But it's a good reminder that for five months a year, driving on wet pavement is the normal commute here, not the exception.

Hydroplaning in one minute

Your tread's job in the rain is to move water out from under the tire so rubber can stay on the road. When water arrives faster than the grooves can clear it, pressure builds under the tire and lifts the tread off the pavement. The tire is now riding on water instead of road.

When that happens, steering, braking and acceleration stop working the way you expect until the tire touches down again. The factors that make it more likely all push in the same direction:

• More speed gives water less time to escape.
• Less tread gives water less room to escape.
• More water, like a puddle or a low spot, gives the tread more to move.

There's no single speed or water depth where it starts for every car, and you should be skeptical of anyone who gives you one. For the physics in more depth, see our Learn guide on hydroplaning.

Why wet roads deserve the respect

The Federal Highway Administration's road weather numbers are worth knowing. Based on 10-year averages from 2007 to 2016:

• 75 percent of weather-related crashes happened on wet pavement.
• 47 percent happened during rainfall.

Snow and ice get the headlines nationally. Rain and wet pavement are what actually dominate the weather-crash numbers, and South Florida gets a lot of both.

Before the storm: the tire side

You can't control the weather. You can control what's touching the road.

Tread depth. The usual replacement line and the wet-weather line aren't the same. The familiar penny-test line is 2/32 of an inch. AAA recommends replacing at 4/32 after testing new tires against tires worn to that depth on wet pavement at 60 mph: the worn tires took an average of 87 feet longer to stop, a 43 percent increase. Our tread depth chart shows both lines in 32nds and millimeters.

Quarter test. Put a quarter upside down in a groove. If you can see all of Washington's head, you're at about 4/32.

Pressure. Set tires to the pressure on your door placard, checked cold. Don't go by the number on the sidewall; that's a maximum, not a target.

If your readings are close to 4/32, run them through Do I Need Tires Yet? before the next storm rather than after it.

In the storm: how to avoid hydroplaning

Here's the short list, drawn from AAA's wet-weather advice and Florida law:

1. Slow down. Speed is the one factor you control on the spot.
2. Turn off cruise control. AAA's reasoning: you may need to slow by easing off the accelerator, and you can't do that while cruise control is holding a speed.
3. Leave more room. Increase your following distance so you don't need hard braking.
4. Avoid sudden moves. No sharp steering or sudden braking on wet pavement.
5. Steer around standing water when you can do it without changing lanes abruptly. Puddles hide depth, and they're where tread gets overwhelmed.
6. Headlights on. Florida Statute 316.217 requires lighted lamps during any rain, smoke or fog. It's also how the driver behind you sees you through the spray.
7. Don't drive into flooded roads. If you can't see the pavement markings under the water, you can't see how deep it is. Turn around.

Before the drive, AAA also suggests checking your tires, wipers, lights and washer fluid, and building extra time into the trip when heavy rain is forecast.

If the car starts to float

If the steering suddenly feels disconnected from the road, AAA's guidance is:

• Ease off the accelerator. Don't stomp the brakes.
• Avoid hard braking. Braking hard while the tires are on water can make things worse.
• Steer gently in the direction you want to go. Small inputs, not a jerk of the wheel.
• Wait for the tires to grip again before making normal steering or braking inputs.

Then, once you're through it, slow down further for the rest of the storm.

After the storm

A few things are worth a look after a heavy-rain season:

• Tread. Recheck depth monthly. Wet-weather grip fades gradually, and it's easy to miss.
• Pulling or vibration. If you hit a hidden pothole in standing water, a new pull or shake is a reason to have the tires and alignment checked. Extreme Tires does alignments in the Sunrise shop.
• TPMS light. If it comes on, check pressures with a gauge and have any tire that keeps losing air inspected.

The whole plan on one card

If it's time for new tires, shop by size and choose installation at Extreme Tires in Sunrise or by mobile van across the local install area. Questions first? Call (954) 773-1896.