Using 4WD in heavy rain?

My 2023 SR5 (Celestial Silver 4D 5' box) has yet to be built (can't wait!) .

This will be my first 4WD anything. Wife currently has a RAV4 AWD that I drive a lot.

The question is: what do you folks do when driving in heavy rain? Do you engage the 4WD or drive it as 2WD? Would driving in 4WD help or hurt anything?

 

Lots of good stuff in here.
https://www.tacomaworld.com/threads/when-how-to-use-4x4.464344/
*heavy rain should be fine, I’d keep it under 55 mph though but that’s just me.

 

May be more than, less than or just some overlap on the other post:
https://www.tacomaworld.com/threads/3rd-gen-traction-control-modes-explained.530695/

 

NO. Not unless you either have really bad tires or it's also freezing, making the chances of ice patches high. 4WD is for low traction situations, it's not AWD. If you find yourself slipping in the rain, maybe just don't punch it so hard or slow down a little.

 

Rain is just rain unless you're on a dirt road

 

Welcome to the forum congratulations on the soon to be new truck.

The Tacoma has a part time 4 x 4 system intended for use in low traction conditions like dirt, mud or snow. It does not have a center differential like the RAV4 AWD system.

If you feel the need to use 4 x 4 in the rain you are driving way too fast/aggressively.

 

There is another post ... cannot recall where right now. It explains that 4WD is literally trying to drive all 4 wheels. If you run 4WD in high-traction environments (dry roads) the difference between the speed of the "inside" and "outside" wheels in a turn (outside wheels must travel faster) causes strain on the differentials. Dirt roads and gravel are good 4WD uses because of natural slipping. Rain situations may be better served by the power-balancing and power reduction actions of traction-control and VSC, which are explained more in the link I sent.

 

Since you mention being familiar with an AWD vehicle and are asking questions on how to use part time 4WD, I don't know if you know the difference between AWD and 4WD. You can find lots of good explanations online, but here's a quick version. When you make a turn, all four of your tires take different paths, resulting in 4 different distances being covered by each tire, resulting in 4 different rpms. This is why you have differentials in a driven system, to allow one tire to spin faster than the other. A 4WD vehicle makes the front and rear driveshafts spin at the same rpm, essentially forcing the front tires to fight the rear ones in a turn. This results in either binding or your tires skipping to release the tension in the drivetrain if you are driving on a high traction surface like a road. In an AWD vehicle, there is another differential in between the front and rear driveshafts, allowing all 4 tires to take whatever paths they want to without them fighting eachother.

 

Here are the links to your downloadable manuals. Page 306 of the Owners Manual says to exercise 4x4 for 10 miles once per month. I exercise 4Hi on a straight road (no turns) after a first rain when roads are slick (not because of rain just to exercise 4x4). Welcome to TW.

https://www.toyota.com/owners/resources/warranty-owners-manuals.tacoma.2023

 

Excellent answer to a valid question.

I pose a question for you. I only occasionally have any real use for 4WD, but I do want to 'exercise' it. Are hard-pack dirt-gravel-roads ok. Technically I
could drive for 20 miles on this dirt/gravel road with zero real need for 4WD, but I am tempted to engage it. Would you think any 'binding' issues
could occur on this type of road?... or should I make excuses to drive from 'ditch-to-ditch' just for a bit of workout.

 

Exercise is partly just to use the fluid in the transfer case and move the gears. Pick any road that has your truck feeling a little bit twitchy for less stress, and use the transfer case for the sake of exercising the internal gears.

 

Yeah, as long as the tires have the opportunity to slip, any gravel should be fine. Also, since binding only occurs in turns, you're always okay to activate it on straight trails no matter what.

 

I use 4wd in the rain every chance I get. But only for a few miles. It’s good to “excercise” the transfer case and actuator.

if you feel you NEED 4wd for rain, you are driving too fast for conditions or you are afraid of the rain.

 

I own a cabin in the north Georgia mountains, and there are miles and miles of gravel roads around my place. This is where I "exercise" my 4WD with no issues.

And I concur with others that using 4WD on hard pavement just because it's raining is unnecessary and potentially harmful to the truck. Now if you felt the need and slipped it into 4WD for a bit on a relatively straight stretch of highway, it won't hurt anything, but I would not make a habit of it.

 

Never had any issues needing 4wd in rain unless on a deep rutted mud swilled dirt road. Only issue if asphalt would be hydroplaning...in that case just slow down.

 

I just use paved straight stretches. You need to do it to keep solenoids shifting and rods moving and gears turning so they will work when needed.

 

Yep I usually go 4x when its a deluge.
Also good to engage all the 4x itms once a month to keep everything moving.

 

Throw it in 4Hi right after/during a fresh rain to exercise the system as needed, its not required for driving dynamics but I figure it's the best chance I have to exercise the system for more than a 1/4 or 1/2 mile as most of my driving is in the city.