Thursday, November 30, 2023


Rain coming? Shut off that cruise control!

By Russ and Tiña De Maris

Everyone’s heard the story of the man driving his motorhome down that long, lonesome highway. Feeling the pull of a “call of nature,” the story goes, he sets the cruise control, climbs out from behind the wheel and heads off for the bathroom.

It’s a silly tale, but one that does have a bit of moral to it. Besides “Don’t drink too much coffee before you hit the road,” there’s the corollary: There are times when you should not use cruise control.

One of those times may not be what you think: in the rain. No, we are not spreading some kind of goofball Internet rumor here. Really. When the rain comes down, so should your speed control. Here are the whys and wherefores.

First there’s what they call “Florida Ice.” Picture yourself cruising along the Interstate, almost lulled by the days of fine weather you’ve been enjoying. But then, here comes that killjoy rainstorm that blows through, wetting up the roadway for the first time in maybe months. During those months of fine weather, the roadway has been accumulating a fine layer of oil and grease from passing motorists. The rain hits that layer, the layer lifts, and you have an instant slip-and-slide setup. We’ll come to the business of cruise control in a second.

Here’s the second rain scenario: the heavy rainfall. If you’ve driven in the Desert Southwest during the hot summer season, you’ve probably met up with our pal, monsoon rain. This isn’t just a nice “put a little damp on” – this is a full-fledged gully-washing gusher that not only makes visibility drop in a hurry, it also puts a thick layer of water on the roadway.

Now in either scenario – oil mixed with water or just plain old “too much water” – comes the driving scare called hydroplaning. With too much water, your tires simply can’t squeeze the water out of the treads quickly enough. With oil mixed with water, the friction coefficient that makes the tires grip the road flies out the window. In any case, the result is an easy loss-of-control where your rig can start spinning out and heading in directions you DO NOT want to go – like for the ditch or, worse, for that loaded gasoline tanker.

Dealing with a spinout or hydroplaning means backing off the gas, staying off the brake, turning into the skid, praying hard, and maybe changing your undergarments when the danger is past. BUT if the cruise control is switched on and your rig hits one of these perilous conditions, it ain’t smart enough to know the expression “Back off the gas!” Cruise control wants you to maintain that set speed, come Hades or high water, and in the case of hydroplaning, you’ve already got the high water.

How do you shut off the cruise control? The immediate reaction is to hit the brake – which, if done too hard, will only contribute to the problem. If you’re smart enough to hold yourself back and hit the cruise control “off” switch, you answered correctly, but by the time you can react and hit it, you may well be mixing paint with a semi-truck. So, says the National Safety Commission, when you see the threat of rain, just shut the cruise control off until you’re “in the clear.”


Russ and Tiña De Maris
Russ and Tiña De Maris
Russ and Tiña went from childhood tent camping to RVing in the 1980s when the ground got too hard. They've been tutored in the ways of RVing (and RV repair) by a series of rigs, from truck campers, to a fifth-wheel, and several travel trailers. In addition to writing scores of articles on RVing topics, they've also taught college classes for folks new to RVing. They authored the book, RV Boondocking Basics.



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Stan W (@guest_143152)
2 years ago

Also, shut off Tow/Haul mode in rain and other slippery conditions. That is what is in the owners manual of my pick up.

Tommy Molnar (@guest_143189)
2 years ago
Reply to  Stan W

I can’t find a thing referencing Tow/Haul and rainy conditions in my 2016 F-350 owner’s manual. Tow/Haul mainly addresses shift points in your transmission.

John Macatee (@guest_143197)
2 years ago
Reply to  Stan W

The “Tow/Haul” only refers to the transmission.

Scott R. Ellis (@guest_105578)
2 years ago

If you’re in the habit of turning off the cruise with a quick light tap of the brake pedal (most will switch off long before ANY actual braking occurs), the extra half-second required to do that isn’t going to make any difference. There are things I worry about whilst driving in bad weather, but this is never going to be one of them.

squaredancer (@guest_77807)
3 years ago

Had my my cruise control/speed controller on and hit a rain puddle-no rain at the time. It can be difficult to hit the brake to turn it off when you’re also attempting to gain control of an out of control vehicle! It wasn’t pretty!

Jim Collins (@guest_76047)
3 years ago

I turn mine off in my car if it starts raining ,just to be safe, and won’t turn it back on until the road is dry.

mike neely (@guest_75979)
3 years ago

I do not think the issue is about your speed controller ( I do not like the term “cruise” control). The issue is the same whether you have your foot on the pedal holding 55 or the speed control is holding 55. If your tire starts slipping the reaction will be the same; you press on the brake the vehicle reacts whether speed control (which disengages) or its not engaged. Usually I have to disengage because the other traffic around me becomes erratic.

Roy (@guest_75856)
3 years ago

I learned to just “tap” the brake to disengage the cruise control years ago. I do automatically now when I encounter rain without even thinking about it. Here’s a tip from my OTR Uncle. In the rain, if you can’t see your tire marks on the road behind you, slow down.

Dan (@guest_76027)
3 years ago
Reply to  Roy

If you can’t see your tire marks you are already hydroplaning. Also not many people drive looking in their rear view mirror all the time, which leads to a MAJOR time lap between spotting the issue and response. This also discounts low spots in the road which hold more water and will seriously impact control.

Roy (@guest_76031)
3 years ago
Reply to  Dan

When I learned to drive I was taught to check the mirrors every 5-6 seconds. I have been rear ended 3 times but I knew I was gonna get hit before it happened every time. Yes if you don’t see your tire marks you are all ready hydroplaning but you can slow down before it becomes a problem.

Billy Bob Thornton (@guest_75844)
3 years ago

Not related but ABS in northern climates has killed more people than the NHSTA will admit. They should put a disarming switch on the dash, that will reset after the key cycles again. Stop forcing systems that can’t be temporarily switched off by the human.

Paul S Goldberg (@guest_82843)
3 years ago

Sorry, spent most of my life driving in severe winter conditions – Rochester NY. Once I learned to use ABS correctly I found it to be a life saver. I was taught in the 60’s to pump the brakes in any skidding situation. That does not work with ABS. The best use of ABS is to jam on the brake pedal and let the system work. Newer anti skid software will even moderate individual wheel brakes to keep you from getting sideways while braking or accelerating. I do have a 4wd Wrangler Rubicon that lets me override all of that as well as lock all four wheel together, but I would hate to activate those at speeds over 25 mph.

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