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Using cruise control during rain

This is a question to satisfy my daughters: Is it a good idea to use cruise control on my AWD Toyota Highlander or my AWD Buick Encore.
I must wear leg braces on both legs and have relied on cruise for speed control. Without cruise, it is difficult to maintain a speed or stay within speed limit if I do not. My daughters have ridden with me when I used in rain. I was told it was dangerous. Is it. Is the danger of hydroplaning greater, even with AWD?

As long as your tires are in good condition, it doesn’t matter if you have AWD or not with regards to hydroplaning.

Modern cruise control plus traction control plus stability control will not allow the car to run-away if you hit a puddle.

Use your cruise control in the rain. I do, always have.

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I hardly ever disagree with Mustangman but this is one of those times that I do . I do not use cruise control in the rain and that seems to be what most web sites say if you do a web search . Also Jim in your case the leg braces just might limit your ability to use the brakes quick enough to cancel cruise if you have a hydroplane situation .
The hydroplaning is really related to tires and that is why the new guide line is that if only buying two new tires only that they go on the rear of the vehicle .

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Yes, I’m agin’ using cruise in slippery or wet conditions regardless of AWD, RWD, or FWD. In my Olds with Posi-traction it was quite dangerous in slippery conditions and could put you into a spin out before you knew what happened. The cruise will try to make up speed by pushing on the gas when you should be letting up on the gas to gain traction. Not a good idea at all in my book. Hitting a bridge deck or low spot in the road with a puddle at highway speeds is all it takes to lose control. My million and a half miles experience anyway.

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Doing our 2x a year ride of 535 mile one way in our 2017 rav4 I had cruise control off and the car hydroplaned during a severe thunderstorm at 65mph. I cannot recall ever having that experience before. 9k miles on good Michelin tires. Maybe awd was a factor, but I do not know what the brains for cruise control would have done. I learned from this board that Cruise control could be bad in certain conditions. Still upright and walking. My daughter says it is an old wive’s tale, it is not that hard to drive without cruise control, watching to see what the consensus is.

Bad idea using CC in the rain or some mountain road’s.

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Like a lot of things, it sort of depends, in my opinion. I use cruise in the rain all the time. But I don’t use it in a torrential downpour where water might be standing on the road, in areas with lots of curves, or hilly areas. If you’re going down a level interstate in light to moderate rain, using cruise wouldn’t concern me.

I injured my right ankle years ago, and holding light, steady pressure on the gas pedal for a long stretch is very uncomfortable.

As long as you are not driving to fast for conditions, I see no problem with using CC in the rain.

Maybe simply too fast for conditions?

I did interstate commute for work late at night for close to a year in the year that had record snow fall. Although, snow characteristics are are different. I didn’t use CC in bad weather. I have a pretty strong and confident feel of the car due to my long driving. And no electronic assistance. Basic mechanical car with ABS only.

I have learnt that it only takes one miscalculation on the vehicle control in bad weather that determines whether you are dead.

I never slowed down as much. Just didn’t use CC.

This article from Edmunds interviews automobile safety experts, and they agree that any cruise control, including adaptive, is not a good idea in the rain.

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I have over 3 million miles driving experience. I use cruise control in the rain all the time. I had a badly broken right leg and after that, it was very difficult for me to hold the throttle down all night on a tractor trailer. Some time during my driving career, the feds mandated that the throttle linkage had to have two springs on it , each one strong enough to return the throttle by itself. 99% of the tractor trailers I drove did NOT have cruise control. I, an a lot of other drivers carried something to hold the fuel pedal down.

It is not as dangerous as it sounds because in an emergency you can put in the clutch or shift into neutral.

If you are sliding, the last thing you want is engine drag on your drive wheels. You want the wheels rolling so you can steer out of trouble.

As far as slowing down in the rain, that only makes sense if road conditions are the limiting factor in your speed. Most of the time your speed is limited by speed limits that are set lower than the roads design speed.

This is my take as well: “it depends.” There’s a stretch on my way to/from work where the speed limit is 40mph. I don’t drive 40 when it’s raining lightly but I do use cruise control. If it’s raining hard I don’t do either.

Most owner’s manuals have warnings against using cruise control in low traction conditions. A wet road is one of those low traction conditions.

Why not let one of your daughters drive? They sound like they’re safe and intelligent drivers.

Hydroplaning is a danger whether you’re using cruise control or not, but what makes using cruise control in low traction conditions dangerous is that it might continue to send power to the wheels to maintain speed when one or more wheels doesn’t have traction.

If you have cruise control turned off, and you feel the car lose traction, whether on ice or due to hydroplaning, you can immediately let off on the throttle and regain control as the vehicle slows down. If you’re using cruise control and you lose traction on all four wheels, the cruise control will continue to operate the throttle as if you have traction.

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I’m not concerned about the OP hitting a puddle so much as I’m worried about the vehicle hydroplaning and losing traction at all four wheels.

Traction control and stability management detect when one wheel loses traction and starts spinning faster than the others, but how do they protect you when all four wheels lose traction?

These systems cut power to the one wheel that has lost traction, but when all four wheels lose traction, like when you hydroplane, will they detect a loss of traction on all four wheels?

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In all fairness, a tractor trailer has different handling characteristics. When you have 6,000-12,000 pounds pushing down on your steering wheels, and 40,000-80,000 pounds pushing down on the other 16 wheels, it’s a lot harder to hydroplane than when you’re driving a 2,500-pound economy car or a 4,000-pound SUV.

When I was a truck driver, I felt a lot safer using cruise control it the rain in a tractor-trailer than I do in a non-commercial passenger vehicle.

Ok… Single wheel splash… wheel hydroplanes from splashing a puddle, wheel spins up so it doesn’t match the other 3, engine cuts power, drops cruise control, stability control reads the yaw sensor and accelerometers to determine whether or not the car is starting to spin, abs control brakes that one wheel so it doesn’t spin up any faster, looks again for a spin, if it sees one it brake the appropriate wheel to turn the car into the spin and stop it.

All this happens in milliseconds. The driver may notice nothing but the cruise control dropping out.

All 4 wheels hit a BIG puddle, so big all 4 wheels start to spin up. Traction control kicks in because all 4 wheels are accelerating faster than they possibly could if they had any traction at all, cruise drops out. Hydroplaning is a speed dependent thing so once the cruise drops out, the hydrodynamic drag of hitting the puddle will slow the car and re-establish traction, whereupon the stability control, which was reading the yaw sensor all along, now reads the yaw sensor to see if it is spinning and brake the appropriate wheel to stop it.

Again, happens in milliseconds. Notice the cruise drops out either way.

Same thing happens if you hit black ice except things don’t slow down to re-establish traction nearly as quickly!

This is why I still use the cruise in the rain, unless, of course, people around me are slowing and speeding up and slowing, like Florida drivers do. Does this make sense?

How does the system discern the difference between loss of traction on all four wheels and low rolling resistance, such as steep downhill with a tailwind?

Do both of the OP’s vehicles traction control and stability management systems work the same way with the same infallible reliability?

When the AWD is under power, the system looks at rate of change of rotational velocity of each wheel. If the car is on, say ice, there is some resistance and the tires rate of change in rotational velocity is a some value, say X, at a torque value or T. If I put the car on a hoist with zero tractive resistance, apply the same torque value, T, I get a rotational velocity change Y which is greater than X. On a hoist, only the rotational inertia of the driveline is the only resistance so it spins up faster than on ice. That difference can be used to trigger traction control.

The steep downhill detection is easy, the yaw sensor has a 3 axis accelerometer. The tailwind drops the engine torque to essentially zero, a hydroplane event will affect each wheel somewhat differently due, especially the heavy front to the lighter rear. The rear will hydroplane first and on a downhill, will start to spin the car which the stability control will correct.

Doubtful, but they’d be close. Not all systems are equally good but both are far more reliable than their human controller. And the systems can do things the driver just cannot like brake ONE wheel to correct a skid or re-establish traction.

+1. Since the speed threshold of hydroplaning tracks with tire inflation a truck tire at 80+psi is going to be much more resistant than a car tire at ~35psi.