Advantages of AWD in snow?

[scott43]

I wish I could kill it all... However when my wife is driving it's good to have it all. Even disabled isn't really disabled in most vehicles. Locking centre diff could be easily implemented in most vehicles and that would be great

 

[Seldomski]

AWD is great for merging into a snowy roundabout. I appreciate it any time I need to apply power and steer at the same time when traction is poor. Now if you do lose traction in AWD accelerating around a corner, you are really screwed since this will happen at a higher speed than 2WD.

If you are braking in a straight line, it doesn't matter which you have.

 

[Tom K.]

In what conditions and situations will the RAV4 with AWD outperform the RAV4 without AWD? In what situations will the be the same.

With near certainty, the AWD RAV4 will wildly outperform the FWD version at resale.

 

[François Pugh]

Horizontally or vertically?

Back to the original subject: AWD is often more user-friendly, especially with torque vectoring, for those who don't know (and don't care to know) much about driving dynamics. That makes it a useful tool for a lot of the American populace.

Personally, I consider the ability to mask slipperiness in a straight line a bit of a mixed blessing—it absolutely allows a faster rate of travel, but if I don't notice that the dash light is flashing, it becomes really easy to overestimate how much grip I have. I prefer proper, selectable 4WD in most conditions, because I can (usually) feel the ass end trying to kick out on throttle before things actually go pear-shaped, and I find it easier to recover from a sliding tail end than a steer axle that's decided to choose a different direction of travel. If things get truly slippery, flip the switch into 4WD and continue on (with the clear realization that expecting a lot of cornering or stopping traction is a horrible idea).

The one place I really miss 4WD auto (available on higher-end Fords and, I think, most GM trucks) is mixed surfaces on 50 MPH roads, like coming over a rise on I-90 and going from clear pavement to wall-to-wall ice and snow.

Re: stopping quicker: Team O'Neil did a YouTube video comparing 4WD vs 2WD stops on snow, with the 4WD winning by a significant margin. I don't know if the results would hold up in an AWD system.

I love those flashing traction control lights, especially if the traction control is unobtrusive and still let's you hang out the rear end a bit. It give's me an excuse to floor it and freak out the passenger.
Passenger: "What are you doing!"
Me: "We have to get away from the snakes!"
Passenger: "What snakes?"
Me, pointing at the warning light: "Don't you see the warning light?"
Passenger: "?????"
Me: It say's, "Snakes following truck" (or car, but last time I played that game it was the company truck )

 

[Ogg]

With near certainty, the AWD RAV4 will wildly outperform the FWD version at resale.

Beyond a doubt it's biggest advantage. Calling any RAV4 "AWD" is being far too generous, IMO. Their system may briefly apply power to both sets of wheels when it deems it necessary but it is not what I would call all wheel drive.

 

[scott43]

Beyond a doubt it's biggest advantage. Calling any RAV4 "AWD" is being far too generous, IMO. Their system may briefly apply power to both sets of wheels when it deems it necessary but it is not what I would call all wheel drive.

Really though, 99% of these vehicles and drivers never leave pavement. The system works magnificently well in its intended role. Is it a locked-up rally vehicle?? Nope..but 99% of drivers aren't locked-up rally drivers! Horses for courses...

 

[Tom K.]

Really though, 99% of these vehicles and drivers never leave pavement. The system works magnificently well in its intended role. Is it a locked-up rally vehicle?? Nope..but 99% of drivers aren't locked-up rally drivers! Horses for courses...

Guilty as charged, and agree 100%.

I owned the "old" Rav4 Sport with the NA V6 engine. What a fun "car" and a tiger in the snow.

Current Sienna AWD with snow tires is unstoppable in it's only important duty of never missing (near) first chair on powder days.

 

[Rudi Riet]

I think the best internet explanation was that something about braking in AWD/4WD in any modern implementation will use some portion of engine braking...

The big assumption here being that the car has an automatic or CV transmission - which (sadly) most modern cars do. Those of us still part of the Cult of the Clutch (or the Three Pedal Army) know that using engine braking is a good thing but needs to be done in a way that it doesn't create a skid as the engine syncs with the transmission. It's a relatively easy skill to learn and master but something that few these days remember how to do.

Agreed with most other points here:

Top notch winter tires are the most important non-driver element (you see a lot of folks in upper New England who drive FWD or RWD cars with full winter rubber and get around just fine in their snowy/icy mess winters)

AWD systems differ wildly, some being the real deal (e.g. Audi, Subaru), other less so (e.g. RAV4 AWD).

Any way you look at it: pilot skill and knowing limitations is the real key. AWD/4WD under the hands of someone who doesn't understand the laws of physics is about as useful as is a paring knife for chopping down a giant redwood. Back when I was driving to northern Vermont ski areas on the regular in a FWD car, I'd pass myriad AWD/4WD trucks and SUVs that had spun off into the ditch along I-91 and I-89. Most of these were folks who lived in less wintry climes (many, many New York, New Jersey, and Connecticut plates) and figured "hey, I have AWD/4WD - I'm invincible!" I'd hazard a guess that most were running all-season tires and that many of these tires were close to their wear limit (read: pretty much bald).

Meanwhile, Mr. Slow Roll in his FWD Geo with snows did just fine.

 

[Dave Marshak]

Those of us still part of the Cult of the Clutch (or the Three Pedal Army) know that using engine braking is a good thing but needs to be done in a way that it doesn't create a skid as the engine syncs with the transmission. It's a relatively easy skill to learn and master but something that few these days remember how to do.

Back in the day, when a RWD Ford Country Squire with bias plys on the front and retread snow tires on the back only was thought to be the ultimate winter driving machine, just toucheing the brakes would skid the front wheels and cause a complete loss of steering control. Engine braking was essential back then, even if it wasn't very effective. Modern cars with ABS and traction control and good disc brakes have made engine braking obsolete, especially if you are running 4 winter tires.

Top notch winter tires are the most important non-driver element (you see a lot of folks in upper New England who drive FWD or RWD cars with full winter rubber and get around just fine in their snowy/icy mess winters)
Meanwhile, Mr. Slow Roll in his FWD Geo with snows did just fine.

This +100

dm

 

[sparty]

Any way you look at it: pilot skill and knowing limitations is the real key. AWD/4WD under the hands of someone who doesn't understand the laws of physics is about as useful as is a paring knife for chopping down a giant redwood. Back when I was driving to northern Vermont ski areas on the regular in a FWD car, I'd pass myriad AWD/4WD trucks and SUVs that had spun off into the ditch along I-91 and I-89. Most of these were folks who lived in less wintry climes (many, many New York, New Jersey, and Connecticut plates) and figured "hey, I have AWD/4WD - I'm invincible!" I'd hazard a guess that most were running all-season tires and that many of these tires were close to their wear limit (read: pretty much bald).

Meanwhile, Mr. Slow Roll in his FWD Geo with snows did just fine.

I'd say it's much more like a homeowner dropping a 30-foot tree with a chainsaw and a prayer. It can work, and with a little bit of training and a bit of extra space cushion, it may work more often than not, even if the operator doesn't understand any of the basic concepts that underly the training. If you have 10,000 people with that same level (lack) of understanding trying at the same time, some of them will probably provide YouTube-worthy video.

 

[slowrider]

It's alot easier to speed up than slow down.

 

[Ogg]

It's alot easier to speed up than slow down.

In some vehicles more than others.
My last truck was a 3/4 ton with hydroboost brakes and a crappy ABS system that was useless on anything frozen. In 4wd it would get going in almost any conditions with relative ease but any contact with the brake pedal sent the system into complete idiot mode. My newer 1/2 ton has a far superior braking system despite having drums on the rear. The ABS/traction/stability system actually works quite well and I have been able on numerous occasions to stop in shorter distances than I anticipated in an emergency.

 

[snwbrdr]

Hello

I have often heard that the main and sometimes only advantage of having AWD in the snow was to get up steep roads or a steep driveway.

What are some of the other advantages give the scenarios below.

For example to make it simple say we compare two vehicles, a Toyota RAV4 with AWD and a Toyota RAV4 without AWD. They both have the exact same new 3PMSF tires, for example the Goodyear Assurance WeatherReady or the Michelin Crossclimate.

In what conditions and situations will the RAV4 with AWD outperform the RAV4 without AWD? In what situations will the be the same.

Assumption - The roads are all well maintained think driving to Squaw from the Bay Area Highway 80 to 89 and local driving around Tahoe. No off road driving.

The AWD RAV4 will get you going from a stop faster in snow and ice.... also if you have to climb a steep hill somewhere, AWD will get you going.

Lastly, AWD RAV4 means you don't need to install chains in a R2 chain control condition. The FWD RAV4 regardless if it has a 3PMS tire or not, has to have chains installed in the R2 chain control

 

[snwbrdr]

Re: stopping quicker: Team O'Neil did a YouTube video comparing 4WD vs 2WD stops on snow, with the 4WD winning by a significant margin. I don't know if the results would hold up in an AWD system.

With an on-demand type AWD system, like the RAV4, in braking, it becomes 2WD. A subaru AWD, Audi Torsen/Crown differential AWD (not Ultra AWD or Haldex), etc since torque is always going to all 4 wheels, it will slow down like a Jeep in 4WD-high

 

[François Pugh]

The AWD RAV4 will get you going from a stop faster in snow and ice.... also if you have to climb a steep hill somewhere, AWD will get you going.

Lastly, AWD RAV4 means you don't need to install chains in a R2 chain control condition. The FWD RAV4 regardless if it has a 3PMS tire or not, has to have chains installed in the R2 chain control

Question is with good winter tires (e.g. studded Hakka 9s), would I need chains in the R2 Chain control condition? That is, do they wait until it's really needed to call it (remembering making it down the mountain without putting on the chains, but regretting not installing them on the way down)?

 

[snwbrdr]

Question is with good winter tires (e.g. studded Hakka 9s), would I need chains in the R2 Chain control condition? That is, do they wait until it's really needed to call it (remembering making it down the mountain without putting on the chains, but regretting not installing them on the way down)?

AWD = no chains needed. You need to carry them.
FWD = chains needed, with studless AND studded winter tires. CA does not consider studded tires to be an approved alternative to chains.

Truck Chain Requirements | Caltrans
If I have studded snow tires, do I need to carry chains?
Yes. Studded snow tires are not considered tire traction devices and may not be used in lieu of chains.

 

[François Pugh]

Yeah, I probably wouldn't want to do too much dry pavement highway driving with studded tires. Also IMHO chains (real ones) beat studs in deep snow.

 

[raytseng]

Question is with good winter tires (e.g. studded Hakka 9s), would I need chains in the R2 Chain control condition? That is, do they wait until it's really needed to call it (remembering making it down the mountain without putting on the chains, but regretting not installing them on the way down)?

on 80 and 50 yes, it will be a checkpoint when R2 is declared
On some of the other smaller highways not considered primary routes, chain conditions maybe listed but not always checked with a checkpoint.
If you choose to workaround with fake badging or bending the truth or avoiding using side streets that may result in heavier penalties should you get caught, plus whatever moral issues you may have on that topic.

I would agree chains, especially higher quality chains and not cheapo ones, will outperform even awd with snow tires.

 

[François Pugh]

on 80 and 50 yes, it will be a checkpoint when R2 is declared
On some of the other smaller highways not considered primary routes, chain conditions maybe listed but not always checked with a checkpoint.
If you choose to workaround with fake badging or bending the truth or avoiding using side streets that may result in heavier penalties should you get caught, plus whatever moral issues you may have on that topic.

I would agree chains, especially higher quality chains and not cheapo ones, will outperform even awd with snow tires.

Sorry for not being clear. I was asking would the driving conditions always necessarily warrant chains when they declare R2, not about the legal aspect. Or does the guy who declares it freak out when he sees a snow flake (edit: like drivers in Toronto on the DVP do when they see a rain drop)? I was also remembering a ride with chains on the floor of the back seat ('cause I was able to get out of the parking lot at the end of the day without having to lay down in the wet snow and put the chains on the wheels) that turned into a very exciting E-ticket ride, drifting every corner and plowing through the deep snow with wheels braked fully locked up on every straight.

 

[raytseng]

i would say it varies.
Keep in mind there are too many factors so they can never get it exactly right so its a percentage scale not an 1time answer of they are overly cautious vs they got it right vs not cautious enough.
If you were stuck in the control line and it turned out to be only slush, this is just a little bit of bad luck of the probabilities.

80/50 are strategic routes so they will be more conservative in setting controls on these highways. 89 and kirkwood routes they definitely go more cowboy and you are left to your own judgement in some degree.

it takes them time to move /setup the checkpoints, so changing the control cannot react as fast to dynamic weather or road conditions. They may keep controls up based on chance next cloud coming may dump even though road conditions are currently at a transitional point. Reverse is true too, I've been in situation on 80 when I just beat the control still setting up and the severity of the first storm impulse dumped hard, and they really should've started checking 15m before.

I would say based on actual results they are not being super nannying but catering to the lowest common denominator driver.

There have been several days this season that 80 ended up having extended closures "due to multiple spinouts". This implies they weren't strict enough with controls vs the other way around.
There have also been some pretty sketchy whiteout visibility days this season, and they still kept it open. The majority of times that I've driven under controls there is a nonzero number of people crashed or are stalled out.