Auto 4WD

I’m considering trading my f150 for a 2026 tundra. I live in Minnesota with a lot of snow and ice on the highways. My concern is being in 4WD in the Tundra vs Auto 4WD in my f150 at highway speeds where your running on dry pavement one minute and snow and ice the next. Can I drive the Toyota in 4WD under these conditions?

 

If the conditions are bad enough to warrant 4wd, I would use 4wd. You do have to be concerned with binding the driveline when turning on dry pavement. Straight line driving is not an issue.

 

On the highway, how fast can you drive in 4WD high setting?

 

As fast as conditions will allow.

 

Fellow MN'n here, welcome.
My suburban commute on a couple 55mph county roads has had me in 4WD a few times. Relatively straight line freeway driving is no problem at speed. If it's bad enough to be in 4WD I'm likely not exceeding 55 anyway.
Remember to click back to 2WD once you reach your destination and before doing any tight turning on dry/dry-ish pavement.

The bigger issue to me was the tires.
The O.E. Falken Wildpeaks that came with my TRD O/R were absolute trash in light snow. Couldn't get rid of them fast enough.

 

LOL....Living in South Texas I have to remember to drive in 4Wheel drive every once and awhile just to keep everything well lubed.
About the only time I need it is on the beach or the dirt road leading back to the fishing lease.
It sometimes makes me question why I spent the extra money for a 4x4.
But then I think back to all the times it's saved my Ass.

 

I believe your concern is the same as mine. How fast can you go in 4 WD? Highway speeds of up to 70 MPH like some parts of the country?

Not sure what you consider “highway speeds”. On Long Island that is 55 MPH. If you have patchy ice on the road you may want to consider a reasonable speed. 4 WD will not prevent you from spinning on the ice.

Also, if the road is dry, shouldn't you go straight in 4WD? When I purchased the truck, the dealer told me the 4WD was for the 2S’s (sand and snow). Turning on dry pavement isn't recommended.
I assume the Tundra would be as safe as the F150 and traction would rely more on the tires.

 

If you want to drive 70mph on snowy, icy roads, go right ahead. 4wd will not keep you from doing that.

 

I'm pretty sure the manual says you should be under 62 to engage/disengage, but no mention of limiting speed once it's in 4wd.

 

My personal opinion:
If road conditions are such that you need to be in 4WD, you have no business going 70 mph.

AWD, 4WD, auto 4WD, makes no difference. You can't cheat physics no matter how many wheels are driven or how they are driven.

 

I'm a big fan of 4A, Yota calls it fulltime 4WD, Torsen center diff. Don't know why Yota didn't do the Torsen in the new gens Tundra and Sequoia. The Torsen is right there on the shelf, it's in the Land Cruiser and Lexus. Much less stressful to put a vehicle into 4A instead of worrying about shifting from 2WD to 4HI and back as road conditions change.

Seemed an obvious thing to do but here we are. Have a great life and donate to charity.

 

Another MN guy here.
Depending on the roads, I sometimes end up switching back and forth.
Especially in spring when the sun melts some roads faster than others.
I am out in the exurbs, and the last snowstorm this spring the roads were pure ice until I got close to the metro. Then it was sporadic conditions with some roads fine and others very slick.
By afternoon all the roads were fine for 2 wheel.
But if using 4 wheel I probably never go above 50 while idiots are flying by me.
I remain cautious and trucks are damn expensive to replace.

Had full time 4x4 in a Grand Cherokee that also had 4hi and 4low. 4hi I would use after a couple inches on road as AWD would start to shimmy. The system was awesome to drive in weather. Too bad the rest of the Jeep was nothing but problems.

 

To answer the OP, despite the snarky responses from others, I had the same concern reading in my 2017 F150 for my 2024 Tundra, but I have very similar snow conditions in Michigan where I live. I switch in and out as I see conditions come and go. I may have miles of dry roads but miles of snow… I keep in 4Hi as needed. Don’t miss my F150. It was a PoS.

 

Patchy roads aren't a problem, but as has been mentioned, tight turns are. 4WD is good up to about a buck-20; I can't say beyond that..

Auto4WD is a bit deceiving - at least how it is implemented in most vehicles. It is very different from AWD offered in the Land Cruiser, 2nd gen Sequoia, and a few other vehicles. True AWD has all four wheels driven at all times, but with some sort of differential (typically a torsen-typel limited slip) in the transfer case to differentiate between the front and rear drive shaft speeds. Just like the axle differential, it allows for effective power transfer at different rates to both sides of the differential. This means that when you turn a corner in AWD, all four wheels can spin at different speeds while still applying power to the ground, without binding the drivetrain.

4WD lock the front and rear driveshafts together, relying on the axle differentials to differentiate speed between tires. In small turns, this isn't an issue. I sharper turns, the wheel speeds vary more front to back than the axle differentials can accommodate and you end up with drivetrain bind.

Auto4WD is simply an electronic monitoring system that engages and disengages 4WD as the computer see's fit, judging by the amount of wheel slip seen at each wheel (taking in to account steering angle, speed, throttle, etc). The default mode for Auto4WD is: front axle engaged, 4wd engaged in the transfer case, but front driveshaft disengaged. This allows the front and rear driveshafts to spin at different speeds and keeps handling very close to that of 2WD. When the computer senses wheel slip, it engages the front drive shaft (usually via a clutch pack and/orsyncros and electromagnetic coupler) to engage the front axle. Else, the front tires aren not driven most of the time you are in 4Auto and not slipping.

My issue with this system is that it is harder on components, and takes corrective action only after wheels start to slip. On ice, IME, that may actually be worse that just letting the back end kick around a bit, as now your front tires may lose grip and compromise your steering. 4WD is much more predictable.

I have about 220k miles on my '13 with similar road conditions in the winter. I just recently converted it to use the sequoia part time AWD/4WD transfer case because it's the "best" system for my use. But between 4wd and 4Auto, I would take 4WD most any day. I've had a few GM products with 4Auto that were virtually never used, favoring true 4WD 99% of the time.

 

What he said…