11-22-2020, 09:51 PM | #1 |
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Physics of hydroplaning
This is a combination question and venting session
I was driving on the freeway today in a relatively heavy, cold midwest rain in my M240i xDrive, visible standing water on the asphalt. Switched over to my winter tire and wheel set last week. Not completely sure how competent the Continental Wintercontacts are in rain, but the tread is still new and deep. I wasn't exactly crawling along (I never do!), running what I felt like was near the maximum safe speed for conditions in a very capable car...and what do I see (repeatedly)? A parade of minivans, SUVs, various beaters overtaking by 10+ mph. Question: Anyone have any data on how effective the Wintercontact TS830's are in the rain? Venting: It's infuriating to be a competent driver in excellent equipment and having to deal with the risk of getting tangled up with folks with absolutely no situational awareness and even less contact with the pavement... |
11-22-2020, 10:20 PM | #2 |
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not hard to find visit continentals web site has everything you could need
https://www.continental-tires.com/ca...contact-ts-830 or if you like a tire rack style testing https://alltyretests.com/continental...p-test-review/ |
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11-24-2020, 08:05 AM | #3 |
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No doubt you have rubber and a tread pattern that can outperform most other tires but that's not the whole story. If you have lots of rubber on the road due to wide tires and not so much weight on them, hydroplaning can be a risk still. A heavy vehicle on skinny tires may have higher capacity for squeezing water from under the contact patch. It is similar in snow.
Not suggesting that you get skinny tires because they would perform worse when you drive on clear or damp pavement, which is probably most of the time. Just understand the limitations of wide tires on snow and wet. |
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11-24-2020, 09:44 AM | #4 | |
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Quote:
If you have the chance, this is a good time of year to take the tires to an isolated spot when it's cold and wet out and see how they behave at the limit, especially the braking limit. That will give you a measure of confidence when you have to stop quickly during your daily driving.
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TC Kline Coilovers; H&R Front Bar; Wavetrac; Al Subframe Bushings; 18X9/9½ ARC-8s; 255/35-18 PS4S (4); Dinan Elite V2 & CAI; MPerf Orange BBK; Schroth Quick Fit Pro; Full PPF |
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11-24-2020, 10:05 AM | #5 |
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My son's college application essay was about the physics of losing control. He attended a Skip Barber safety course at Lime Rock and at the direction of his instructor was supposed to apply throttle as he entered a curve. He didn't listen and lifted off causing the 550 hp Viper to spin out onto the grass around the track. He definitely learned his lesson and spent a bit of time picking grass from the tire/wheel junction. That essay got him into Brown ( and almost caused my own brown out as I watched him spin!).
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11-24-2020, 04:48 PM | #6 |
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You've got to be careful about assuming that straight wet braking distance is any indicator of resistance to aquaplaning, especially on a bend. Quite a few recent video reviews have concluded that the selected winters had poorer wet braking than all-seasons. However when I've looked at some of the German magazine reviews, where they use a lot of instrumentation, they've concluded that the winters chosen were significantly more resistant to aquaplaning than any other type, especially when they set up a test on a curve. I also noted that on one of the recent UK video reviews, while driving circuits, they said how much better the winter's handling was on wet curves, but this never made into the summary at the end, when all they quoted were the straight-line, braking-to-a-stop distances. I find it a bit confusing as it's always been my experience that the winters have been much more sure-footed in heavy rain and standing water, but of course, that's purely subjective. Also, given that there are huge differences between brands of the same season (summer, winter) tyres, aren't you also going to get differences between brands across seasons too?
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11-24-2020, 05:47 PM | #8 |
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A lot of the braking issues of winter tyres are caused by the generally lateral siping causing the tread blocks to fold over under braking. Some tyres (such as Sottozeros) have more random siping direction and tread blocks that lock together under braking, but lose out slightly in acceleration and braking grip on snow. With the Michelin X-Ice XI3 tyres I have used in the same size as Sottozero 3 tyres, you can feel the tread blocks on the X-Ices give way on wet and dry surfaces under hard braking, leading to a 23% increase in stopping distance compared with the Sottozeros on a wet surface.
https://www.tirerack.com/tires/tests...y.jsp?ttid=193 https://www.tirerack.com/tires/tests...y.jsp?ttid=181 |
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11-24-2020, 06:39 PM | #9 |
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I just went with staggered Michelin Pilot All Season 4s to replace my 3 year old square setup Michelin Alpin PA4s. Wet braking, dry braking, and handling outside of snow driving were compromised massively with the PA4s for winter driving in Kansas City. I get the need for dedicated snow driving capable tires in certain areas of the world, but for as little snow we see on roads here in the winter (10 to 20 days), the compromise in the cold and wet was just too much and All Season 4s offer more safety in cold conditions I drive in.
And yeah, most people drive too fast for conditions and most people's driving skills in an emergency situation are terrible. |
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11-26-2020, 08:08 AM | #10 |
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Thanks @aerobod and your links were interesting in suggesting that because my last two cars have had Pirelli Winter Sottozero (Serie-II and S3 respectively), that's probably why I have the view that winters are much more resistant to hydroplaning than the summers, because they are, especially in the case of my current S3s.
It also underlines the danger of generalising across different seasons to say that all winters are inferior to all summers re hydroplaning. Just take a look at my Winter Sottozero S3s (right) compared to my summers (left): On the basis of my own experience, the S3s are simply better than my summers in heavy rain and standing water in the colder winter months. And when you look at the area of the tyre with drainage channels and the much more extensive routes for water to escape, this should come as no surprise. No doubt someone will rightly point out that my stock Continental summers aren't the best brand to chose from, but that also sort of proves the point about how difficult it is to make generalisations, even within the same-season brands, let alone between seasons. A while ago I had a long discussion with someone who asserted that summers, having mainly straight drainage channels (as on the left), were the most efficient at moving water from under a moving tyre. So I did a bit of research into some of relevant tyre industry published research, which indicated it wasn't that simple, or true. Around a 20° angle of the drainage channels shifted the maximum water (which may explain why some of the all-seasons are good, because trads like the CrossClimate are very diagonal). But as someone referenced, having the whole tread with angled channels was not good for braking, so it's something of a trade-off.
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11-26-2020, 12:59 PM | #11 |
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Also, front wheel drive cars with the engine mounted far forward are like a dart thrown, they have great straight line stability.
And for the x-drive M240, when driving fast in the rain you really only need a very light grip on the steering wheel, Let the wheel jiggle a little as it encounters the variations of grip. |
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11-27-2020, 03:58 AM | #12 |
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This is a great thread. Right now I am wrestling with the speed that the tread hits the water on a wet road. Say the car is moving at 88fps (60 mph) how does that compare to a much slower speed? If I dive into water at 88 fps it will be more like hitting concrete due to inertia of the water and surface tension. Two very different effects. But wait, the tire comes down into the water at a much slower speed. If the water is very shallow that speed approaches zero so inertia approaches zero while surface tension remains the same.
Also, hydroplaning is different depending on how much of the tread is floated and how thick the layer of water is between the rubber and the road. And how that water is moving will have some effect. Last edited by Shovelman; 11-27-2020 at 05:49 AM.. |
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