Winter tires, once you've seen / touched them, are visibly different: different tread, way softer rubber, etc. I also pretty much always use studded tires, as we've been getting a lot of freezing rain in the last few years, and the one accident I've ever had was due to that (fell in the ditch while driving at ~30 km/h. I had a hard time _walking_ on the road without slipping).
The flip side is that they're more likely to skid on pavement, especially in summer. That's why you have both.
Exactly, tires are the single most important element of winter driving. If you live in a place with mild winters all season tires can get you far, but if you get a lot of snow or ice seasonal tires are critical.
Cold tires are slick tires that will slide all over hell and back, the tread on winter tires is designed to better move slush and snow out of the way so the contact patch can hopefully reach the road surface; while the softer rubber heats easier so it can get to a nice 'grippy' temperature and grab hold of the road even in conditions where the wet and cold are trying to sap heat from it.
During the warmer months these winter tires will be less effective because they have smaller contact patches (due to more/deeper grooves in the tread to drive moisture away), and will actually get hotter than desired (softer rubber) causing a loss of grip as the rubber will want to start shearing off instead.
Everyone needs to remember no matter what fancy engine, electronics, etc. your car has - your tires are the only thing that actually touches the ground. Acceleration, braking and turning are all highly depending on their ability to grip the ground (and withstand the forces being placed on them) - so make sure you have the right ones and don't put off replacing ones that are nearing the end of their life.
In winter situations, it's stopping (and steering) you need to worry about, not going.
(Said as someone who drives a BIG 4x4 with excellent winter tires in a part of Canada where they are required by law)
People aren't stupid. There's a reason why everyone who can swing it buys an AWD to commute and not everyone buys snow tires. The snow tire is still gonna be slush-o-planing any time you go onto highway slush of appreciable depth. Heck a mud tire with big fat grooves is your best bet when the tire is on that. There is no tire (suitable for general use, I'm sure the Florida mud racing crowd has something up their sleeve) that can handle that without planing. There just isn't enough space between the tread blocks for all that viscous fluid to be forced through (assuming you're going like 20+mph) and you end up on top of it.
Being able to change lanes and enter traffic from side streets/driveways with less slip is just a soooooo much better experience than not being able to do those things gracefully but in exchange for a slightly a better worst case stopping distance in fairly rare conditions (ice and fresh powder).
Commuting in snow is nothing like those commercials where they drive on ice. All the traction in the world won't help you when your problem is that the tire isn't making contact with the road. Driving on ice and fresh powder are so rare it's no surprise that consumers don't optimize for that. Sure you can put snow tires on your AWD but the lions share of improvement in the conditions people actually encounter comes from AWD.
I speculate most snow & slush under compression has some shear strength to offer even though there is little dry friction.
If conditions are bad enough to cause a FWD or RWD car to hydroplane then there’s nothing AWD can do to help it given the same tires. Grip is all that matters when it comes to staying put on the road, and that comes entirely from your tires on normal road cars (most road cars aerodynamic profiles generate lift rather than downforce, so you aren’t getting any aero grip unless you are driving a sports/supercar with aero elements).
How can anyone say this with a straight face?
Spreading the motive power out over twice as many tires does a ton to help.
As you drive through that slush would your rather be trying to put all the vehicle's motive power through two tires or four?
Do you dispute that doubling the number of tires moving the vehicle forward will drastically reduce the ease with which the vehicle breaks traction crossing over the slush?
Grip and traction are two words for the same thing, the only thing that determines grip are the tires plus the weight (and distribution thereof) they are carrying. So, yes, having AWD does nothing to help grip - that's a mechanical force between your tires and the road.
AWD helps utilize grip, by distributing torque to all four wheels. It helps acceleration by avoiding wheelspin where two driven wheels don't have the grip, but nothing else.
Edit: Clearance is more important when trying to cross over piles of shit on the road anyway. It doesn’t matter how many wheels are driven on your car if you bottom out.
I've also noticed when driving AWD cars on sand and dirt they are stable at higher speeds than FWD.
The thing is, AWD makes it easier to get going by letting you put engine torque through all four tires. The same set of tires has the same mechanical grip regardless of how many wheels are driven, so if a FWD car would spin taking a corner at X speed due to lateral load so will your AWD car (and the AWD will have an easier time doing it).
Sure both cars would descend the same, but you can always lower your speed to decrease the amount of traction you need. When climbing there's no such options for FWD.
When it comes to winter driving the entire perceived benefit of AWD vehicles for commuter use goes out the window as soon as you need seasonal tires, basically. Yes, it will still better help put the power down given equal tires - but at that point the extra cost of the AWD system isn't giving you too much benefit if you are only buying it for winter driving.
I've heard the FWD + snow tires beats AWD + all seasons before and personally I don't believe it, but it's a pretty subjective thing. The big win for AWD is predictability and control, not that I want to go around corners sideways at 100 mph rally style. Having control over the car, even when sliding, without any rear or front bias just makes for a MUCH more controllable car.
My Subaru forester with AWD and all seasons handled numerous treacherous conditions, sometimes so bad that every highway around me was closed. I used to do 6 7200 foot passes every weekend, often in the middle of storms dropping 2-3 feet. My main problem on the roads was others that don't know how to drive and block the roads.
I've driven roads so slick that going too slow would cause you to slide off the road. I'd have to apply torque, while sliding, to keep the 10-15 mph required to avoid sliding to the inside of every banked turn. Which would be MUCH harder with FWD or RWD.
Amusingly at chain control points, often the workers would look back in the line, see my Subaru and pull me out of line and let me go through with a smile and a wave. Presumably because there are (or weren't anyways) any non-AWD Subarus (this was before the BRX) and Subarus aren't the typical cars getting stuck and causing problems.
Sure AWD and snow tires is even better, just seems overkill for the highways in the high sierras.
Braking in AWD scenario and traction are not same as your example and depends on the power split between the front and rear and how the 2 are coupled together. In 4WD with the 50/50 split, the drive shafts are locked together through the differential and braking is much more effective in part due to the fact that the braking is more evenly distributed among the 4 wheels since the drive shafts are locked. Also when you lock up the brakes in 4WD usually 2 wheels on the diagonal keep turning, again due to how the differentials work. This is not the case in FWD.
There is something seriously wrong about either my understanding of how cars work, or yours.
I have brake disks and brake pads on all 4 wheels of my (FWD) car; pretty much every car does. How would a drive-shaft help "distribute" braking power? The limiting factor here isn't the force each brake can exert on their wheel (they're pretty much always able to lock up), it's the traction between the wheel and the ground (the tire).
In my mind, an "ideal" emergency braking scenario would be all 4 wheels braking at the maximum force they can without slipping, and that can be done much better by the ABS system when they're all disconnected from each other. A driveshaft connecting them would be irrelevant at best, but more likely it's a nuisance.
AWD is complicated with 3 differentials that can be a mix of open, limited slip, or actively controlled (by torque split or brake based system). It's especially tricky since it's not the actual traction that matters as much as the driver perceived traction and predictability. I've drivin AWD systems with snow tires that seemed to have more traction than my subaru with all seasons, but ended up driving more slowly because I couldn't predict what it was going to do. Subaru seems to communicate well with the driver, and making sliding just not a big deal. Other cars make it harder to tell what a given throttle/braking input is going to result in and can trigger heavy front or rear bias based on what the sensors/software tell it to do. It drives me nuts when a car acts completely differently in high traction and low traction conditions, especially when it changes one second to the next. Some Subaru folks make fun of other systems that they call "slip and grip", where there's a heavy FWD bias (minimal torque to the rear), until AFTER you start slipping.
My WRX had a limited slip in the rear, center diff was a viscous coupling (100% mechanical/no software), and a open front diff. It was reassuring, never surprised me, and even when significant slipping I could always put the car exactly where I wanted. Even when crab crawling sideways in a parking lot at 2 mph it never surprised me. Numerous Toyota, Ford, Honda, and BMW cars I tried would try to outsmart me. Limiting throttle, moving the torque around, limiting braking forces, etc. Last thing I want when climbing a hill is the car to cut the throttle because one of 4 wheels slipped for 50ms.
Consumer reports tested a Subaru forester, Toyota RAV 4, and Honda CRV in heavy snow conditions and concluded the Subaru was a clear winner despite them all having similar dry road performance and AWD.
I think for normal snowy roads Subaru does it best with a mostly manual system, the ABS and traction control has a light touch that can be mostly avoided. But for heavy offroad the best thing to do (in certain messy conditions) is lock all differentials, which is something the Subaru can't do.
It's obvious that it'll help when accelerating, and perhaps even when turning, with a (more) even application of torque on all wheels.
My main gripe with it is that it often gives drivers a false sense of security (as they got going easily), and they'll drive too fast for the conditions. Just look at some parts of this sub-thread, where people say "I don't need winter tires, I have AWD / 4WD".
If you need to brake in an emergency on snow / slush / ice, nothing is going to help you except your tires (and perhaps some smart ABS).
There's a wide variety of software solutions as well, some work better than others. It's a non trivial problem. For instance. In normal conditions less braking when any wheel slips is best. In slippery conditions for stopping or going some slipping is best. In really messy conditions it can be best to not keep applying torque (in the positive or negative direction) without any "smarts". For emergency braking in the snow it can be best to just lock them up and have snow build up in front of the tires.
To see an example of how big a difference this makes, check out
https://www.consumerreports.org/video/view/cars/auto-test-tr...
I agree that AWD leads to overconfidence to some, I've been driving at 35 mph on the highway (with a 65 limit) in my Subaru (with good tires) in bad conditions and had giant SUV blast past me at 10-20 mph over what I was doing ... only to find them in a snow bank later.
Doesn't mean that AWD wasn't a huge help. My first AWD was a result of me spinning out in a FWD around lake tahoe in poor conditions, in heavy traffic, at 10 mph or so. My front right tire lost traction, the open front differential put all power to the front right tire, and it spun me into a snow bank (just 18" away") in a blink. I was quite impressed how much rotational acceleration could happen in a blink of an eye. The open differential meant I was basically 1 wheel drive (when slippery), the car I replaced it with (Subaru WRX) had 3 wheel drive (when slippery) and was MUCH more predictable. In fact sliding in the snow would bring a smile to my face... and I changed my weekly commute (6 7200 foot passes) to maximize the snow involved.
And yes I'd MUCH rather have all seasons and AWD instead of snow tires and FWD. It's not the ultimate traction as much as being predictable. Sure all seasons have less traction, but it's way more predictable and gives much better control when sliding. FWD, even with snow tires can be very unpredictable, and can easily spin a car when the traction is low. Subaru + snow tires seemed overkill for the roads I was on. Sure Subaru + all seasons might be safe in some conditions at 35 mph, snow tires might raise that to 40 or 45 mph, but FWD regardless of tires would mean much less, and Caltrans would require the pain of installing and uninstalling chains and worries about chain failures and/or damage to the car.
Even with all seasons, my main fear with a Subaru (I've had two) is hitting enough snow to life the tires off the ground.