Driving in snow - 2wd or 4wd

[Ryland]

Being able to stop is more important then being able to go, 4 wheel drive hurts stopping distance, if for no other reason that it makes the vehicle heavier.

I just added towing to my progressive insurance policy, $1 per month and I can use it 3 times every 6 months.

[Fat Charlie]

Originally Posted by pete c

Also, not all TC is created equal... My 2009 Sonata's TC is complete garbage. Most of the time, it just kills power. I have actually turned it off in disgust to be able to get up a hill.

Most systems "control" traction like people try to control crime. They don't want it getting out of hand. Wheelspin detected? Kick in the ABS. Problem soved: no more wheels spinning!

In any snow at all, or in the wet in certain locations, turning it off is just another part of my routine. I'd rather be a little busier than have the shock of brakes being applied for me when what I want and am expecting it the exact opposite.

Originally Posted by Ryland

Being able to stop is more important then being able to go, 4 wheel drive hurts stopping distance, if for no other reason that it makes the vehicle heavier.

Correlation is not causation. Most 4/AWD rigs are just plain too heavy for "stopping distance" to be anything more than a sick joke even before the extra drivetrain gets counted. And speaking of dodgeball victims, they invariably have automatics. It's a trifecta of excess weight, lack of gear control and sloppy power input.

My Subaru was the bomb. Yes, the drivetrain (and the turbo...) held down my gas mileage. But with a manual transmission, control of the driven (count 'em, 4!) wheels was unsurpassed. Slightly lifting the throttle introduced deceleration evenly in all four corners. Coming off entirely or downshifting let you do it with more force. With the engine it's all smooth and controlled, reversible with a thought- your foot never leaves the pedal. Not as clumsy or random as pads clamping down on rotors; an elegant system for a more civilized driver.

Stopping distance? You can slow well enough to not need to stop.

[user removed]

I think we drove the wife's Murano in 4wd less than 10 miles in 32k miles.
RWD is not bad on snow, but ice-freezing rain is another thing altogether.

regards
mech

[SDMCF]

Originally Posted by Ryland

Tirerack.com did some tests a few years back with tire pressure and traction on snow, they found that with low pressure they lost traction and recommended full pressure.

I had a look at Tirerack.com but I could not see the test you mention. Do you have a link to it? The result directly contradicts my own experience and I would like to look at the test to try and understand how/why they reach that conclusion.
One issue is that winter conditions can vary so much - far more than summer conditions. Perhaps in fresh deep snow higher pressures may be better; I am not sure on that and have never tested it. For packed snow or ice I have always found low pressures to provide much better traction.

[solarguy]

Note that studded tires beats everything if you are on ice, but are illegal for most states and most people. In Michigan, the postal delivery folk are allowed to have them...

[wdb]

Just a quick "ditto" of others' comments that 4 winter tires are hands down the best choice no matter which or how many wheels are driven.

Originally Posted by Fat Charlie

Correlation is not causation. Most 4/AWD rigs are just plain too heavy for "stopping distance" to be anything more than a sick joke even before the extra drivetrain gets counted. And speaking of dodgeball victims, they invariably have automatics. It's a trifecta of excess weight, lack of gear control and sloppy power input.

First you knock AWD, then you sing its virtues? I'm confused.

My Subaru was the bomb. Yes, the drivetrain (and the turbo...) held down my gas mileage. But with a manual transmission, control of the driven (count 'em, 4!) wheels was unsurpassed.

Depending on which Subie you had you may have had 3, or possibly even 2, driven wheels. Center diff might always send torque front and rear but front and rear diffs are not all LSDs. My STi on the other hand... w00t! That car was so much fun in the snow it was probably illegal.

My winter tire cautionary tale occurred in a different Subaru, with winter tires (my first-ever set) and 3-wheel drive. We were coming back from the airport on a wet winter day. Everyone was barreling along in spite of the conditions, as usual. Crossing an overpass I thought I felt the car slip a bit, as if the bridge surface had frozen over. I looked up the road and sure enough cars were spinning every which way on the next overpass, bouncing off the guardrails and one another. I did not feel safe making a panic stop due to the traffic volume, so I picked my way through the ongoing carnage. Got out the other side unscathed, looked at my wife, and said "that's it - winter tires from now on".

I have a 4WD Tacoma now. The 4WD is nice on snow-covered roads but nowhere near as effective overall as my AWD Subies. It's designed for ultimate offroad traction, and the differences are noticeable. Snow-covered woodland trails, on the other hand, are the Taco's happy domain.

[Fat Charlie]

I was knocking the overweight SUVs that tend to be what gets 4/AWD.

In a small or midsized car it can be as great as I said. The only real knock against AWD is that while it's better than FWD, FWD isn't actually bad so AWD doesn't give you all that much- I've never decided to stay home because I "only" had FWD.

My Subaru had the "symmetrical" AWD, which I think was all 4, all the time.

[kafer65]

I've seen some amazing feats of driving in the snow with fwd being able to vector the drive wheels up hills but I've gone tush-up in a ditch with my old Subaru Forester because I broke the front loose trying to turn and accelerate out of my driveway on ice. My kids still bring up the amazing donuts we could do in that Forester in the snow. Good times!

[RedDevil]

The video a few posts back shows how snow tires have twice as much grip on ice as all weather tires, and that's good. Studded tires do even better on ice, as mentioned.

Where snow tires really stand out is (predictably) in snowy conditions and especially just below freezing, on a road with a layer of hyper slippery flattened snow and some fresh new flakes on top - conditions all too common in our moderate winter climate.

That surface is very treacherous with ordinary tires, where the snow fills up the tire thread so the wheel is like a solid ice disk, making the upper layer of snow underneath melt under the contact pressure. Grip is even lower than on ice.

The thread of snow tires though has small ruts and soft rubber.
This prevents the snow from packing solid in the thread. Thread pressure will still melt the top layer of snow, but that escapes into the thread recesses.
Moreover, the finer detailing of the thread means it matches the small aberrations in the road surface better instead of riding and gliding on the tops.
It does not just have twice as much grip, like it does on ice.
It has ten times as much grip or even more.

I have scared myself so many times before with all my previous cars and their all season tires, that I have difficulty assessing the grip level of my current winter tires.
I cannot bring myself to exploring the limits as they are so far beyond what I was used to.

[star_deceiver]

There are very few states that outright ban studded tires, and of those the laws only apply to residents of said state. The other states only have date restrictions.

http://www.rma.org/tire-safety/seaso...e-regulations/

Never had a problem driving in WA, OR, or CA outside of the permitted window.