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On Subarus, 4/AWD & Snow Chains...

post #1 of 60
Thread Starter 
It was a dark and stormy night...

A few years ago, on my way up to Tahoe, I had a brief chat with the poor soul manning a highway 50 chain control checkpoint during the slow, snowy overnight shift. I asked, "Is there ever a situation where I would require chains on my Subaru (AWD Legacy)?"

The answer I received was a very definitive "NO". Other law enforcement officers, CalTrans personnel and high-country residents have indicated the same.

However, a lot of low-landers I work & play with (some 4WD owners) seem skeptical of this advice, and a current thread here (Snow chain required to sugarbowl) would seem to indicate the advice I've received may not be entirely correct.

FWIW, I chuckled to myself Thursday morning cruising the crud up Hwy 80 from Auburn when I breezed by a Subaru Forester with chains on the rear wheels only.

From experience, I know the Subarus (at least the manual transmission variety) are very sensitive to minor differences in front vs. rear tire diameter. If I wait too long between tire rotations, giving the front tire the opportunity to wear down sufficiently more than the rear, I begin to develop an noticable and irritating (and mechanically harmful) driveline vibration.

Point being, if I were in a situation where I'd use chains in a Subaru, I would presume I would want them on all four tires.

This might not be the case for other manufacturers' "AWD" vehicles where front and rear output is not coupled full time.

A quick web search dug up this interesting thread on the subject: http://forum.ski.com.au/scripts/ulti...2;t=000014;p=0

Here's an informative excerpt from that thread, a reply from a Subaru engineer:

"Many thanks for your email. To answer your question, yes- the Subaru All-Wheel-Drive system meets the exemption & snow chains would not be required.

"Our Chief Engineer has recently made an enquiry to VicRoads & received this reply:

"1. VicRoads did not release any bulletins, acts or regulations related to snow chains and A-W-D vehicles.

"2. The VicRoads Act states that snow chains are required on Buses that carry over 12 persons.

"All Subaru vehicles from approx: MY1997 are fitted with a permanent All-Wheel-Drive system. If for example a front wheel looses traction, the drive will go to the rear. The drive is always available at both front and rear wheels, unlike some other brands that wait until wheel slip occurs. In addition to this & dependent upon model, some pre-MY1997 Subaru vehicles were also fitted with an All-Wheel-Drive system.

"The Subaru owner's manual indicates that driving on snowy grades or icy roads may require the use of snow chains, in which case put the chains on the front wheels. As to when the chains are required, this is determined by Government regulation or the directions provided by the Authorities in the snow field/park that you enter.

"If the front and rear wheel sizes vary; and the vehicle is driven over a prolonged period, eventually damage can occur to the Viscous Coupling centre differential fitted to manual transmission Subaru's, or to the Transfer Clutch fitted to automatic transmission Subaru's.

"The A-W-D Subaru Automatic Transmission is fitted with a full time All-Wheel-Drive transfer clutch that is electronically controlled. This ensures that the vehicle maintains 50:50 traction levels at the front and rear wheels. Torque transfer is dependent upon tyre to road contact to ensure no wheel slippage occurs.

"The A-W-D Subaru Manual Transmission is fitted with a Viscous Coupling centre differential, which transfers a full time 50:50 drive to the front and rear wheels dependent upon tyre to road contact to ensure no wheel slippage occurs.

If you look at the Subaru All-Wheel-Drive system as a whole, in both Manual and Automatic transmission. Based on their operating principles, the Subaru A-W-D system outperforms most other 4WD systems; hence snow chains may only be required in extreme conditions on the front wheels for steering purposes, NOT for tyre to road surface slippage."
post #2 of 60
Funny that you should mention that. Today on US 2 in Washington State, they're requiring chains on all vehicles.


The Stevens Pass report:

Temperature: 35ºF / 1ºC

Restrictions Eastbound:
Traction Tires Advised, Oversize Vehicles Prohibited.


Restrictions Westbound:
Chains Required All Vehicles Including All Wheel Drive


Conditions & Weather:
Compact snow and ice on the roadway. // Rain and snow mixed
post #3 of 60
Well CalTrans has five levels of chain controls ...
  • Open with no controls
  • R1: Chains, traction devices or snow tires are required on the drive axle of all vehicles except four wheel/ all wheel drive vehicles.
  • R2: Chains or traction devices are required on all vehicles except four wheel/ all wheel drive vehicles with snow-tread tires on all four wheels.
    (NOTE: Four wheel/all wheel drive vehicles must carry traction devices in chain control areas.)
  • R3: Chains or traction devices are required on all vehicles, no exceptions.
  • Closed
Note that both R2 and R3 technically require chains. When I 'phoned our local CHP office they said they rarely, if ever, bother with R2. And realistically if it's R3 it's really not worth being out there. Also, realistically, CalTrans really can't be bothered with arguing with 4WD owners on I80 and 50 and just close the road rather than dealing with R3 and the carnage it would create. SUVs are a pain to pull out of the ditch.

I have a Subaru with snow tires and no chains. I have a K2500 with studded snow tires (which haven't been mounted this season : ) and no chains.
post #4 of 60
I don't know California regulations. The post directly above this one seems to indicate that chains may theoretically be required, but maybe it just never actually happens. There are other states in which chains are sometimes required for all vehicles.

Putting aside regulations, and turning to the practical world, there are conditions in which you car won't go without chains (or, sometimes, even with chains). Not typically encountered on highways, but certainly on smaller roads or parking lots.

A properly-designed AWD system should work with chains on only two wheels. It will, of course, have better traction with chains on all four wheels. But chains on two wheels (I'd do front, rather than rear) will be better than no chains.
post #5 of 60
Thread Starter 
Quote:
Originally Posted by sjjohnston
A properly-designed AWD system should work with chains on only two wheels. It will, of course, have better traction with chains on all four wheels. But chains on two wheels (I'd do front, rather than rear) will be better than no chains.
Your choice of front rather than rear is affirmed by the Subaru tech in his final paragraph, for steering control if nothing else. For the health of the drivetrain, all four would be better.
post #6 of 60
I don't carry chains for my Volvo XC70, either. If it is R3, stay home or in town and wait it out.

I think I have only seen R3 on Rt 88 in 14 years of skiing in Tahoe. Never on i80.
post #7 of 60
Thread Starter 
Quote:
Originally Posted by StormDay
II think I have only seen R3 on Rt 88 in 14 years of skiing in Tahoe. Never on i80.
Well, I don't know what "R" rating they were calling it early on Thursday morning, and although it wasn't snowing at the time I was driving it, I have never seen 80 (nor 50) in such an unplowed condition. It looked truly as if we were driving through a snow field, with no discernable tire tracks.

Coming back down Saturday evening in that monster of a storm (jeez, what an incredible day to be at Sugarbowl!!!), the highway was "clearer" (passed many a plow), but traction / drivability much worse.
post #8 of 60
Quote:
Originally Posted by speede541
Well, I don't know what "R" rating they were calling it early on Thursday morning, and although it wasn't snowing at the time I was driving it, I have never seen 80 (nor 50) in such an unplowed condition. It looked truly as if we were driving through a snow field, with no discernable tire tracks.

Coming back down Saturday evening in that monster of a storm (jeez, what an incredible day to be at Sugarbowl!!!), the highway was "clearer" (passed many a plow), but traction / drivability much worse.
Probably was still only R2 (no chains for 4WD/AWD). In some low snow level storms (<3K), I think cal trans just does not have enough plows to cover all the miles. I have been on i80 in around 8" snow in some spot from Blue Canyon to Truckee.

BTW: On i80, black ice scares me the most. When I first move to CA, living in Grass Valley, i80 got shut down a couple time for black ice. People were stranded on the interstate for up to 12 hours. :
post #9 of 60
Last time I saw Caltrans require R3 on a major highway was about 10 years ago. However there are situations where I might choose to put chains on my old Legacy. Despite 4WD my car has slid around more than I like when several inches of snow gets on a road surface before it has been plowed on steeper hills. Putting chains on imy front wheels in that situation adds noticeable extra traction. ...David
post #10 of 60
I've never seen R3 on i80 either and usually when it happens, Caltran shut it down.

However, on a snow-wheeling trip with some friends last year around Eagles Lake, coming back on I80 we got caught in a very fast moving cold storm that dumped about 4-5 inches in a very short time. Then it got really cold and freezed.

Man, I've never seen so many accidents in one stretch of freeway before. I was in 4wd in my Pathfinder and sliding left and right. I saw all kind of cars in the ditches, from Honda Accords, Camry's, Mini Van, some Subaru and Mercedes SUV too. Because we went 4wheeling so many of us have tow straps to help pulling people out. In a condition like that, even with 4wd, I don't think it's even drivable (safely of course).

They shut the freeway down for 3 hrs to clear it.
post #11 of 60
Some of the newer Subarus can't really accomodate chains in front because of limited clearance between the tire and strut. That may be why they had them on the rear (thinking that was better than not at all).

When I asked about this, most long-time Subaru owners said CalTran wants to see chains in the car, but they rarely (if ever) ask AWD drivers to put them on. I guess the rule is that you have to be "carrying" them.

The issue with tire rolling circumference mismatches is only a problem when driving extended distances. For less than 50-100 miles, don't worry about it. Same issue when you put on a temporary spare and that's obviously something they allow (again for limited distances).
post #12 of 60
My Audi manual says no chains if using the factory-issued wheels, which I assume means if you get smaller wheels then chains are okay.
post #13 of 60
For cars with limited clearance in the wheel wells, you might consider getting Spikes-Spider traction devices. Because it's rare for Highway Patrol to require chains for AWD cars, I'd have a hard time justifying the expense or the space these take up in the car. When I had a mini-van, though, I did use Spikes-Spider because they were my only option.
post #14 of 60

4 x 4 and Snowtires

When road restrictions (in the Cottonwood Canyons in UT for example) say "4 x 4 or Chains Required", I'm assuming AWD is included under 4 x 4 and not just 4WD? (Otherwise, every Suburu wouldn't be allowed.)

I had it explained to me a long time ago, but I'm still not totally literate on the difference between AWD and 4WD anyway. What are the pros/cons of each as it relates to travel in snow, ice and/or rain?

Also, I've seen "Snowtires or Chains in Your Vehicle" requirements. If you have an AWD or 4WD vehicle with "All-Season" tires, are you OK without having chains with you? Along those lines, is there an official designation on a tire that qualifies it as a "snowtire" in this context? (As a sidenote, isn't pretty much every tire that's not sold as a special winter snowtire considered "All-Season"? I've never heard of "Summer-only" tire!)
post #15 of 60
Thread Starter 
Quote:
Originally Posted by Wags
I had it explained to me a long time ago, but I'm still not totally literate on the difference between AWD and 4WD anyway.
Honestly there are so many variables amongst each type that the differences, as they are typically explained, are done for the purpose of demonstrating one brand's superiority over another.

The major difference between 4WD and AWD is the use (or absence) of a transfer case.
post #16 of 60
Quote:
Originally Posted by Wags
Along those lines, is there an official designation on a tire that qualifies it as a "snowtire" in this context?
Yes. There's a symbol stamped on the sidewall of "snow" tires: a jagged mountain-ish shape with a childish sketch of a snow crystal.

Most tires are, indeed, "all season," and are marked "M + S," which stands for "mud and snow."

Different states treat these differently, in terms of what passes muster in what conditions, just as they do with AWD.

There are non-all-season tires. They're more common, I think, on cars that are set up to be performance or sports cars, rather than drive-all-over-the-place vehicles.
post #17 of 60

Sports car

You're probably right about tires meant for sports cars. I used to have a sports car and I doubt those performance tires would have been too great in the winter snow (even to an "all-season" level). Of course, I lived in Florida at the time so I didn't put too much thought into that concern!

By the way speede541, so a "transfer case"-- would that be like carry-on luggage!? No one will ever confuse me with Click and Clack the car guys!
post #18 of 60
Quote:
Originally Posted by Wags
I had it explained to me a long time ago, but I'm still not totally literate on the difference between AWD and 4WD anyway. What are the pros/cons of each as it relates to travel in snow, ice and/or rain?
The two extremes:

True 4WD means all 4 wheels are driven and locked together. This only works offroad or on slick roads, where you can slip the wheels in corners to prevent the drivetrain from binding.

AWD theoretically drives all 4 wheels, but does it in such a manner (using slipping differentials) that you can drive on dry pavement all the time.

Most vehicles fall between these two extremes, and marketing confuses it further. So what one manufacturer calls 4WD or AWD will be different from another manufacturer. Some manufacturers (for instance Subaru) may have multiple types of AWD across the model line (Subaru has 4). And many "AWD" vehicles (Hondas in particular) are really FWD until the front wheels slip, at which point the rears start being driven. Such part-time AWD systems give you the benefit of FWD for fuel economy most of the time, and the benefit of AWD on slippery roads. But they are not as versatile or balanced as a true AWD vehicle which gives traction/driveability benefits in all conditions.
post #19 of 60
Thread Starter 
Quote:
Originally Posted by Wags
By the way speede541, so a "transfer case"-- would that be like carry-on luggage!? No one will ever confuse me with Click and Clack the car guys!
Transfer case as in a second transmission, of sorts, that mechanically and positively (through gears) drives all four wheels.

The alternative would be some sort of clutch or viscous coupling that has the ability to transfer power to all four wheels, but doesn't necessarily (i.e. you could somehow bind up or block the two front wheels, but the rears would continue to be driven.
post #20 of 60

Best combination i have come across, and i have owned awd, subarus, 4wd trucks, all sorts of cars. I had a 86 awd audi quattro with studded snow tires all round, it had full time rally inspired awd, and you could also lock the centre differential between the front and rear and if things got realy bad lock the centre and rear all together, it never got stuck, i used to test it in parking lots with snow so deep it was coming over the hood. The problem with trucks is they still have solid axles (60 year old technology) which limits traction as one sides movement effects the other etc, go for independant suspension on a modern european or jappanese awd car you cant beat it.

post #21 of 60

This Washington State Stevens Pass restriction is surprising.  I don't think I've ever driven anywhere in Washington and seen chains required on all vehicles.  I lived most of my life there and only had studded snows on front wheel drive cars.

post #22 of 60
Quote:
Originally Posted by speede541 View Post

It was a dark and stormy night...

A few years ago, on my way up to Tahoe, I had a brief chat with the poor soul manning a highway 50 chain control checkpoint during the slow, snowy overnight shift. I asked, "Is there ever a situation where I would require chains on my Subaru (AWD Legacy)?"

The answer I received was a very definitive "NO". Other law enforcement officers, CalTrans personnel and high-country residents have indicated the same.
 

 

Went through two 24" + storms last season in my 09 Forester with only the cheezy all season Duelers under her.  I would, however chain up in a situation where there is solid ice on the road everywhere from sleet or serious thaw and refreeze-and the road hasn't been sanded yet at all.

 


 

Quote:
Originally Posted by skier219 View Post

Some of the newer Subarus can't really accomodate chains in front because of limited clearance between the tire and strut. That may be why they had them on the rear (thinking that was better than not at all).
 


That is my scenario.  I had two sets of chains from my previous exploits but actually gave one set away because there isn't any travel at all in the front wheel wells of the 09 Forester.  If I do ever chain up it will be rear only and for only as long as absolutely necessary.. if ever..
 


Edited by crgildart - 11/24/10 at 5:03pm
post #23 of 60


 

Quote:
Originally Posted by skier219 View Post

Some of the newer Subarus can't really accomodate chains in front because of limited clearance between the tire and strut. That may be why they had them on the rear (thinking that was better than not at all).

When I asked about this, most long-time Subaru owners said CalTran wants to see chains in the car, but they rarely (if ever) ask AWD drivers to put them on. I guess the rule is that you have to be "carrying" them.
 

My Subaru manual says to not put chains on it. I was concerned about this and called the road authority for I-80 and asked about chains. The person I talked to said they would close the road  before requiring chains on AWD vehicles but that I was required by law to carry chains (that fit) in R2 situations. I bought the cheapest chains I could find and just keep them in the back for show if requested. That was probably a waste since I'll probably never be asked to show them.
 

post #24 of 60

I've had many conversations with Caltrans Superintendent's and Supervisors who oversee highway 88 & 50 and also many CHP officers who work in the high country. 

 

They all confirmed that if it ever gets to R3 (Chains on all vehicles, NO EXCEPTIONS) the highway is simply closed.

 

 

.....

 

 4WD/AWD with chains on all 4 tires > 4WD/AWD with chains on 2 tires > 4WD/AWD with Snow/Ice Tires > 4WD/AWD with M+S tires

 

Basically, chains on a 4WD/AWD drive vehicle are smart if you are willing to take the time to put them on. 

 

Also, many modern 4WD vehicles act just like AWD vehicles

 

Check out this link for a great comparison between chains on all 4/ chains on 2/ no chains with studded tire/ no chains on snow tires

http://www.4x4abc.com/ML320/ml_chainss.html

post #25 of 60

That was interesting, but frankly it's ICE I worry about, not packed snow.  And to get up my hill has never been an issue UNLESS it's solid ice.  Like the local church group has been there illegally using our hill to sled all day....

post #26 of 60
Quote:
Originally Posted by sibhusky View Post

That was interesting, but frankly it's ICE I worry about, not packed snow.  And to get up my hill has never been an issue UNLESS it's solid ice.  Like the local church group has been there illegally using our hill to sled all day....



I've had to help 4wds get out of ditches while driving a front-wheel drive with limited clearance and Thule chains that was bomber in snow or ice so long as plowing was regular.  For the vast majority of people chains and common sense are all they will ever need for resort skiing, and the chains they'll only need once or twice a year and only if they want to push it.  (Most people will heed current advice to not get chains of course.)   Everything I drive now is 4wd, but I also may get chains this year to help on ice.  4wd is much, much better than awd when there is patchy slick ice, but no good when the ice is uniform, so even with a real good 4wd chains can be very helpful in special situations. 

post #27 of 60
Quote:
Originally Posted by CTKook View Post



Quote:
Originally Posted by sibhusky View Post

That was interesting, but frankly it's ICE I worry about, not packed snow.  And to get up my hill has never been an issue UNLESS it's solid ice.  Like the local church group has been there illegally using our hill to sled all day....



I've had to help 4wds get out of ditches while driving a front-wheel drive with limited clearance and Thule chains that was bomber in snow or ice so long as plowing was regular.  For the vast majority of people chains and common sense are all they will ever need for resort skiing, and the chains they'll only need once or twice a year and only if they want to push it.  (Most people will heed current advice to not get chains of course.)   Everything I drive now is 4wd, but I also may get chains this year to help on ice.  4wd is much, much better than awd when there is patchy slick ice, but no good when the ice is uniform, so even with a real good 4wd chains can be very helpful in special situations. 

most 4wd vehicles only drive one front wheel and one rear wheel, it takes  positraction differentals or locking diffs to get all 4 wheels as drive wheels, even a 4wd with a rear posi only drives 3 wheels, some awd cars  drive all 4 wheels all the time, so saying 4wd is better than awd  isn't always correct. most 4wd do have the advantage of ground clearance over AWD 

 

post #28 of 60

You know, if I only had chains for two wheels, even if for a front wheel drive or 4 wheel drive car, I think I would put them on the rear for coming down the mountain.  But really, if your going to get two, you may as well get 4.

post #29 of 60

N.Z.ski areas have some pretty scary roads, and freqently require chains on four wheel drives. One day Bodie Miller and the US ski team were first up and blocked the Coronet Peak road. Once traffic came to a stop only the vehicles that had chains available were able to get moving again.Some cars were sliding backwards down the road.   I have driven Subarus for 23 years now and always carry chains. Getting up the hill is much easier than getting down. Their is nothing more scary than sliding down with no control and all wheels locked.

I use chains on the front wheels. This gives more directional control.    

post #30 of 60


 

Quote:
Originally Posted by darent View Post



Quote:
Originally Posted by CTKook View Post



Quote:
Originally Posted by sibhusky View Post

That was interesting, but frankly it's ICE I worry about, not packed snow.  And to get up my hill has never been an issue UNLESS it's solid ice.  Like the local church group has been there illegally using our hill to sled all day....



I've had to help 4wds get out of ditches while driving a front-wheel drive with limited clearance and Thule chains that was bomber in snow or ice so long as plowing was regular.  For the vast majority of people chains and common sense are all they will ever need for resort skiing, and the chains they'll only need once or twice a year and only if they want to push it.  (Most people will heed current advice to not get chains of course.)   Everything I drive now is 4wd, but I also may get chains this year to help on ice.  4wd is much, much better than awd when there is patchy slick ice, but no good when the ice is uniform, so even with a real good 4wd chains can be very helpful in special situations. 

most 4wd vehicles only drive one front wheel and one rear wheel, it takes  positraction differentals or locking diffs to get all 4 wheels as drive wheels, even a 4wd with a rear posi only drives 3 wheels, some awd cars  drive all 4 wheels all the time, so saying 4wd is better than awd  isn't always correct. most 4wd do have the advantage of ground clearance over AWD 

 


Exactly.  For ice specifically, the problem with AWD is that if one wheel has good traction and one is spinning on slick ice (or very slick snow), you can effectively be shut down.  Where a 4 lo or a true 4 with lockers has no problem.  This is not a normal driving condition, obviously, and where you're on a more uniform surface very slick surface, like what you'll often find driving to/from ski areas, AWD then has advantages.  Some 4wds have AWD as their "normal" state until "4wd" is engaged, but a lot of people also misuse 4wd, or even think that driving, say, a 4wd F250 in "regular" RWD mode makes them safer "because it's a 4wd." 

 

For ski resort access, unless you're really pushing it there are very few times where you really need more ground clearance than you get from, say, an Outback, or even a Honda Odyssey.  I also agree with the O.P.  that if you're going to chain up on an Outback, putting chains on all 4 tires takes about 5 more minutes and makes a lot more sense.  For people whose cars have clearance issues, you can get chains designed to work with very limited clearance, there are a couple of excellent online chain vendors.  And for people with 4wd, if you'd want chains on an Outback -- say, a ski area neighborhood with a significant thaw/freeze where you pretty much know you'll have to gun it for several hills if you don't have chains, and where you KNOW you'll see several sport utes into the snowbank in certain spots -- you should get them for your 4wd.  But, for those same conditions you wouldn't need them as a vacationer to get from the airport to the ski area condo.  Edit:  AWD and good snows you may well need...chains likely not, 4wd almost certainly not, and for ski area access the chains make more sense than the 4wd.


Edited by CTKook - 11/26/10 at 4:52am
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