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Slippery when wet? Driving in the rain

While driving in a downpour at 65 MPH I was thinking that in my driver’s ed class (in '63) we were always told never drive over 55 or you would hydroplane. And yet here I am doing 65 and people are passing me doing more than 70 or 75. So is the old advice obsolete? Is the engineering for roads and tires that much better? Or are people just plain stupid drivers?

Cars, roads and tires are much better now days. But it is still a good idea to slow down in the rain. Especially right after the rain has started, all the oil and dirt is still on the road and the water makes it a slippery mess.

There is not a magic speed number for hydroplaning. Tires , road conditions and amount of standing water will be the most determining factors. I also think you are remembering a discussion more than an actual statement.
This can’t be the first time since 1963 that you have been passed in the rain .

It is recommended to turn off cruise control, just as a reminder.


Hydroplaning happens when the tires can’t evacuate the water they are running through so you essentially “float” on top of the water. Bad news - as you can’t steer or stop. Many people can feel when the car is about to hydroplane and slow down. Some just crash.

Tread depth and design affect how much water can be evacuated at what speed. Brand new tires with deep tread and many grooves are the best. Bald tires with minimal grooving are the worst. Everything else is in between.

Add to that roads that do not drain away water very quickly, flat roads with no crown, low lying roads that flood a bit, things like that made hydroplaning more likely.

You can’t just say “faster than 55 mph is bad” because the real answer is “it depends on the condition of the tires and the road”

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I never drive faster than 60 in a medium rain, heavy, 50.

Stay in the right lane, and don’t think of the idiots passing you doing 70. That is their problem. I long ago learned to not compete with speeders.

Remember, those idiots will get to their destination only a few minutes sooner than you would. Are those few minutes worth the increased risk?


Driving instructors say a lot of stupid things. I took a road test for a car hauling company and the tester told me I could not change lanes on a curve or I would jacknife, That was particularly preposterous because we were doing 30 mph on a curve that would allow 70 and it was a dry sunny day.


Besides slowing down, there are some other key things to remember, especially in the Northeast at this time of year.

  1. monitor your tires and make sure you don’t start the wet season with worn tires. The “standard”, 3/32" thread depth, is really an absolute minimum and not really safe in wet weather.
  2. wet leaves are like grease. A young friend got in a serious accident today on wet leaves on a curve. It’s too early to know to full prognosis.
  3. make sure you have good windshield wipers and clean headlights. Being able to see as well as possible in bad weather has saved many a life. Far too many people underestimate the importance of clean headlights and good windshield wipers. If you’re not sure, change them.

I’m sure this list will grow. But I absolutely had to get that point in about the wet leaves, a friend being in the hospital on morphine as I write this because of wet leaves… and inexperience.

Oh, yeah, the question: tires, cars, and roads have all improved. Unfortunately, common sense and physics haven’t.


Tire width and air pressure are also factors. Skinny high pressure tires are less likely to hydroplane than wide low pressure tires. A 10-speed bicycle tire inflated to 120 psi will be the last tire to hydroplane.

One of the warning signs that you are on the edge of hydroplaning is a small four cylinder car starting to spin the front tires when you give it the gas at highway speeds in fifth gear.

Recently, a lot of our freeways starting to be paved with a porous asphalt designed to drain standing water from road surfaces. I-35 between Austin TX and Buda TX being a good example of this new technology.

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Oldsmobile’s top-of-the-line luxury car in 1965, the Ninety-Eight Luxury Sedan, came with 14 inch wheels and tires of bias ply construction that featured tread not much deeper or more aggressive than that on my kid’s Schwinn bicycle. The power steering and alignment angles combined to make the steering and roadfeel floaty at best, and the best way to tell where the car was headed was by looking at which way the hood was aimed. The drum brakes were a real treat too. Nonetheless, I loved driving that car, even though it was 25 years old by the time I had it.

Everything is better these days. I feel safer in my late model Explorer doing 75 in the rain than I ever did in that 65 Olds at 55.

Big 10-4 to that, Barkydog. I lunched the torque converter on my 2005 Dodge Dakota when I got a little bit of air while traversing a steep bridge approach (OK going up the approach, caught air when it leveled off. Cruise control thought I wasn’t going fast enough and revved the engine. When it landed the rear tires were going way too fast to handle the landing and the torque converter went Tango Uniform). The same situation might apply if the rear tires were to lose traction in the rain with the cruise control on.

On the other hand, I had the cruise control on while driving in a light misting rain in my 2015 Jeep Cherokee. When the front tires lost traction, the cruise control thought I was trying to go too fast. The cruise control disengaged and the brakes were automatically applied, slowing the car drastically.

Bottom line: NEVER use cruise control in any conditions in which traction could become an issue.

People that assume that engineering for roads and tires are that much better are stupid drivers.


Both roads and tires are engineered much better than they were a few decades ago, but it is very difficult for even the best engineering to overcome the “stupid factor”.

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Nothing is foolproof because fools are so ingenious. Do not remember where that came from :princess:

Consider it this way; better engineering on the tires, roads, and cars can keep you out of trouble when you would have gotten into it 45 years ago. Go faster than you would have 45 years ago and you erase that margin of error. Do that and you’re in just as much danger even with the new technology as you would have been in 45 years ago. Maybe more, 'cause you’ll be going faster when you hit the tree! :smiling_imp:

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Always think safety when driving in the rain. Road and tire technology won’t save you when you go faster.

No doubt wide tires are easier to hydroplane! Big tires on light cars. Corvettes and Porsche Carreras are great examples of that.

A lot of research has been done in hydroplaning in the last 50 years. It isn’t so much that the idea of keeping the speed below 55 is wrong, it’s that it is too simplistic.

Tread depth and water depth are among the many things that affect the vehicle speed where hydroplaning occurs. Also, hydroplaning isn’t an On-Off kind of thing. Even at low speeds, hydroplaning causes some loss of grip - and the question is: Is that enough to cause the vehicle to go out of control? A very high cross wind can cause even vehicles on dry roads to lose control - imagine what it’s like on a wet one.

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I disagree with that! Both will help keep you in contact with the road and that gives you control. Control will save your life.

Not if you go even faster because you think the road and tire technology will save you… :stuck_out_tongue_winking_eye:

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