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Wednesday, August 15, 2018

The Real Danger Of Rain and Tire Grip.


Rain, Rain, And More Rain
    It's been raining...a lot..here in the Northeast. Pretty much every week (or day!) we experience a downpour. I mean, if I was in Seattle...I'd understand, but I'm not. And this is supposed to be summer! Aside from keeping us inside our RV's (there's lots to do in there too!) it makes traveling a bit more dangerous than when it's dry outside. First, there is the obvious problem of visibility. That's reduced. But what about your tires' lack of traction or "grip" in the rain. Sure, tire technology has come a long way and tires do operate more safely in the wet. But it still pays to be careful. Probably the most dangerous thing is a condition knows as "Hydroplaning."

A Tire Hydroplaning
OK...what is it? Well Hydroplaning is defined as "to slide uncontrollably on the wet surface of a road." It happens when your tires have more water thrown at them than they can disperse and it builds up a sheet underneath, separating your tire's contact patch from the road. I'm reasonably sure all of us who drive have experienced this. One second you are driving along on a wet road and all is well, then the vehicle loses grip and you have no way to change direction or slow down. Sometimes it only occurs for a second, but under the right circumstances, it can go on long enough to cause a crash. It's especially dangerous in the first 10 minutes of a rainstorm as the water mixes with oil on the road and creates a slick surface. Is there anything you can do to prevent it?

Well, yes. Some of the things you can do are quite simple. First, SLOW DOWN! Most hydroplaning incidents happen at above 35 MPH. So, if it's practical, slow down. Next, make sure your tires are properly inflated and have plenty of tread depth to dissipate the water. Avoid driving where you can see long stretches of standing water on the road. Try and avoid quick changes in direction or hard braking in the wet. Most of these (if not all!) you should be doing anyway. The best defense against this dangerous situation is being mindful and aware of changing road conditions.

This is a serious topic. RVs are heavier than most cars and, because of the extra mass, are harder to slow down and control even in normal conditions. Add lack of traction and it could all end in disaster. Above all, be careful! When in doubt, find a safe place to pull off the road (NOT the shoulder!) and wait it out. You've got all the comforts of home....use them!

Be Seeing You...Down The Road,

Rich "The Wanderman"
www.thewanderman.com

10 comments:

  1. Good advice - all of this. In fact, everything you own in your RV inventory benefits when you slow down, regardless of the weather conditions.

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    Replies
    1. MrTommy,
      So right....MPG too!

      Rich "The Wanderman"

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  2. I’ve always followed the rule of not using cruise control in the rain. Is this true or a myth?

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    1. Unknown,
      The main reason to NOT use cruise control in the rain is you aren't controlling your speed and may get into a situation where you didn't want to be going that fast and have to slow down. far better to have complete control in adverse conditions.

      Rich "The Wanderman"

      Delete
    2. Actually, the problem was that the cruise control could add power (or take it away) at an inappropriate time, or add too much power on a slippery surface causing tire spin or a spin out. New cars with stability control may avoid that somewhat. I saw a formula for hydroplaning that related to tire pressure, I think it was hydroplaning would occur a speed in mph equal to nine times the square root of the tire pressure in psi. So, for a car with 30 psi tires it would occur at about 50 mph, which matches my experience. That would mean a motorhome with 100 psi would not hydroplane til about 90 mph, but I have no desire to test that and hope no one else will either. And, that doesn't consider ice or oil on the road.

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    3. William,
      Excellent, detailed information!

      Rich "The Wanderman"

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    4. I will second Forbes' explanation for avoiding Cruise in rain or snow or ice... It is/was all about the timing of power and sensing of speed. The CC may "decide" to goose power or invoke a gearshift just as you hit a slick spot, breaking traction "randomly" where your foot would be gentler and much faster to remove power the instant a slide started.

      The second problem kicks in here: early cruise implementations (especially pre-ABS/ATC) apparently used simple rpm or vacuum sensors to monitor speed, and could go into positive feedback during a skid - the lower engine load of slipping wheels would punch the throttle even more, worsening even mild slips. I had an 1980s van that exhibited this SEVERELY by flooring the throttle if you skidded at all during cruise. Why the reduced load wasn't "seen" the same as going down a hill, and responded to by *reducing* throttle I cant explain, but experienced.

      ABS/ATC/DBW/OBDII have (I think) corrected this latter feedback tendecy by cars sensing when they skid and much smarter CC using that data, but nothing replaces a skilled driver in more direct control. I generally DON'T use cruise when towing, even on dry pavement.

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    5. Wolfe,
      Well said! Sometimes I believe that adding more computer tech to vehicles can become self defeating. My helicopter has mechanical fuel injection and basic electronic ignition. K.I.S.S. BTW: did you receive my email? If not...check spam!

      Rich "The Wanderman"

      Delete
  3. I kick the engine brake off my 6.7 diesel under wet conditions also. A down shift may cause loss of traction on wet surfaces too.

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    Replies
    1. Captn,
      Excellent suggestion...engine braking or downshifting can break traction as well.

      Rich "The Wanderman"

      Delete

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