[Tor3]

> I'd heard the folklore that snow tires are more important than all wheel drive for handling on both snow and ice

All wheel drive helps zero with winter conditions, except for going uphill or some other acceleration-equivalent action. Quite the opposite really - many people have experienced how with 4x4 you don't get a warning before you just lose your grip and off the road you go. For the record I'm driving a 4x4, but using summer tires in the winter, with or without engaging 4x4, the car will simply be like Bambi on the ice. Going downhill would mean that I wouldn't stop before hitting something or ending up in the sea. 4x4 doesn't matter for that.

The first thing I do when getting a new car (I always by second hand cars - not that I buy them often, but I'm old enough to have gone through a few) is to buy the best possible summer and winter tires I can get, particularly the latter. That goes before any other investment in the car. I had enough of bad tires when I was very young and without any money.

EditAdd: Many people comment about ice and studded tires. Yes, studded tires are better, not just on ice, but on many kinds of packed snow conditions as well. For some conditions they are the only good option (interestingly enough, this does not always mean that they're better than studless tires on all kinds of ice - it depends on the ice). However, if there's a lot of bare asphalt around, as is often the case when there's a lot of traffic, then studs aren't particularly popular (road wear etc), and in some countries in Europe with lots of bare roads in the winter they're illegal (e.g. Germany IIRC).

As for winter tires without studs, on ice, be aware that there are great differences between brands and types. My father's car had stud-less winter tires while my car had studded tires, and I drove both cars on the same roads and his car behaved well, even on ice or "glassy" snow. But then the tires got old and he replaced with brand new tires, but a different type - much newer, so should be better, right? Not so. Very different to drive. Dangerous I would say, and in fact he got into an accident because of that. I checked that place with my own car afterwards, and no doubt his old tires would have held up just fine.

[supermatt]

AWD != 4x4. AWD + traction control absolutely helps driving on snow and ice with appropriate tyres.

If you are driving with summer tyres on ice, then of course you are going to be skittering all over the place.

When going downhill on ice, again your tyres are going to make ALL the difference. You shouldnt be trying to stop going downhill on ice anyway. You should be descending at a constant and controlled speed.

[alkonaut]

I think "AWD" today is used to mean "anything that isn't 2WD". So whether it's a full time 4x4 or something that is mostly-fwd-but-rwd-when-slipping or something else isn't part of the nomenclature. It simply means "something more than 2WD at least some of the time". There has been an endless debate as to whether 4WD or AWD are the same or different, whether only "symmetric" or "full time" counts as one or the other. But these days with hybrid drives, traction control shifting drive front/back etc., it's just too complex to keep apart any more.

[supermatt]

Not really - AWD is effectively non-braking traction control by varying the power distribution to each axle (and on some modern electric drivetrains, each wheel). 4wd provides constant power to both axles.

[alkonaut]

I think of it more as an outdated distinction. First of all with motors on each wheel and no communication between front/rear in many cases, the distinction becomes blurry.

Further many manufacturers have names like “AWD” (volvo and others) or “4matic” (MB) or “4motion” (VW) to label their take on more-than-2wd, whether or not their variant is awd or 4WD (or both) in the traditional sense. Some "AWD" models will be electric with 1 motor per axle, or 3 motors (1 front 2 rear) etc. Some others are ICE with traditional drive shaft to the rear wheel axle, which in some cases will drive 50/50 and in some cases variable. Others still are hybrids wth no prop shaft but instead a rear electric motor etc.

[supermatt]

Its not outdated. There may be multiple variations on AWD (as i mentioned, some can vary power to individual wheels, rather than just the axles), but 4WD (or 4x4) is categorically not AWD.

[alkonaut]

Doesn't traction control further blur that? Given that traction control is now required almost everywhere, and involves cutting power to individual wheels (Not like ESP using brakes), at what point does traction control cutting power to individual wheels or axles dynamically in a 4x4/4WD system make it an "AWD" instead?

Perhaps those vehicles that use 4x4 in the tradtional sense are such that you have to engage it and that effectively cuts also any traction control - and then you disengage for normal driving?

[brookst]

I think there is more nuance here. A 4x4 with a locked center diff and open front and rear diffs acts just like many AWD implementations.

That same 4x4 with limited slip diffs on front and/or rear is just like other AWD implementations.

And that same 4x4 with locked front and/or rear diffs is just like yet other AWD implementations.

[sandworm101]

>> First of all with motors on each wheel and no communication between front/rear in many cases, the distinction becomes blurry.

Which cars have motors on each wheel? That is maybe 0.01% of vehicles on the road. (Electric busses?) And even then, AWD/FWD distinctions can matter in how those motors interact. Electric or IC, so long as power is delivered through four wheels there will be different styles and techniques for balancing that power for whatever reasons occur at a particular time.

[supermatt]

Nothing yet, but the next porsche electric drivetrain supposedly will:

https://newsroom.porsche.com/en/2019/technology/porsche-engi...

[meetingthrower]

Agree. We have a Tacoma that has 4WD and it is the absolute dumbest implementation. Contrast that to the Subaru with AWD and it is a completely different driving experience. We go with studs on the Tacoma for that reason, and get by with regular snows on the Subie.

[Tor3]

It doesn't mean any difference when you're trying to slow down downhill. As you're saying, "your tyres are going to make ALL the difference." Which is exactly what I said - 4x4 or AWD doesn't help anything with that.

[supermatt]

Well actually... 4x4 is worse for going downhill on ice. If one axle loses traction (which would be much more likely on summer tyres), the other can initiate a slide.

This is the exact reason people dont like 4x4 on ice. AWD (usually) lessens the problem - which is why i said they absolutely help with the correct tyres.

And again - DONT SLOW DOWN when going down hill. Your brakes WILL lock a wheel and you WILL slide. Slow down BEFORE you go downhill. If you havent experienced this truth, then you havent driven downhill on ice (which is preferable).

[bombcar]

Yeah 4xAWD (let’s piss everyone off) helps maintain action when you’re driving IN the snow (you have a slightly better chance of not getting stuck if you can power all your wheels and have appropriately calibrated antislip).

But losing control because of ice can happen no matter how many driven or traction control wheels you have. And all wheels are basically skis when you’re skidding at 90° to the direction of travel. In fact, in some skids front wheel drive will be the best as at least you have a chance of powersteering out.

The real trick is to not start the skid at all. Sloooooooow down before you’re driving sideways.

[supermatt]

> In fact, in some skids front wheel drive will be the best as at least you have a chance of powersteering out.

Yep, this is actually why AWD is (usually) better than 4WD, because it can drive the single axle, treating it as a 2WD.

[quickthrowman]

Why would you try to slow down (with your brakes) while going downhill on a snowy road? That is the worst possible thing you could do. Go slower at the top of the hill or let off the gas to reduce your speed.

[adql]

> AWD != 4x4. AWD + traction control absolutely helps driving on snow and ice with appropriate tyres.

Too late buddy. The way manufacturers abused AWD, 4WD and 4x4 terms they can mean anything now

[supermatt]

Which manufacturer is using AWD incorrectly?

[falcolas]

Dodge. They call their Charger implementation AWD, but it’s RWD only until a slip, then it engages the front axel.

They fooled me, and it drove like crap on snow. Always wanted to slide.

[sethammons]

> All wheel drive helps zero with winter conditions, except for going uphill or some other acceleration-equivalent action

What are you on about? Living in Montana, AWD is dramatically better than 4WD. And winter tires are great. We never used them on one of our AWDs because the AWD is so dang good. Snow tires were absolutely required on our 4WD and 2WD cars. AWD or snow tires, I am mindful of stopping distance.

I will always choose AWD for the snow. Then add snow tires if needed.

[sandworm101]

Winter driving cover a broad range of conditions, from "I see snowflakes" to "are we still on a road?" Alleged "snow tires" that are good enough in the former can be next to useless in the later.

I helped an AWD SUV/crossover thing ten feet off the road a couple weeks ago. It was in very deep fluffy/dry snow, half on its side, sitting its weight on the snow rather than the tires. Only one wheel actually turned (front left). The AWD/TC system was literally out of its depth. 4WD, potentially with locking diffs, would not have had that problem. Once we pulled it enough to get some weight on the wheels, the AWD system kicked in and helped drive it back onto the road.

The guy had what he thought were snow tires (snowflake mountain symbol) but looking at the treads myself I didn't see the small grooves that imho are typical of proper snow tires. They looked like all seasons perhaps with some extra silicon to qualify for the badge.

[krupan]

If the weight of the vehicle is not on the wheels then locking diffs or snow tires won't help. If you are high centered you are high centered and you have to solve that problem first.

[sandworm101]

Typically, when you go off the road with some speed you will be high on the front but less so on the back. In this case we couldn't really tell as the rear wheels were not turning (AWD likely defaults to FWD for most driving conditions). In these cases I don't like digging around too much for fear that the car will settle/shift onto someone. We grabbed at the front bumper tow point, rotating the car 45* counterclockwise. At some point during this the rear axel decided to start helping and it half drove itself back onto the road.

[zamadatix]

Summer < summer + awd < good all season < good all season + awd < winter < winter + awd

Is my opinion from living in Michigan i.e. AWD is always a step up but rarely better than having the right tires. It depends a bit on the conditions too - are you looking out the window and wondering if your car will get stuck/make it up an incline or are you looking out the window wondering if your car is going to slide into a into a ditch/the car in front of you or is it an equal mix? AWD adds the most value when there was a heavy snow, unplowed roads, and relatively low traffic since. In any other case it’s really not all that helpful, except maybe a slippery uphill intersection but even then good tires help there and the inverse situation whereas AWD only helps in the one direction.

[evancox100]

AWD or 4WD does nothing for you if you’re braking and trying to stop.

[brookst]

And snow tires do nothing if your two drive wheels are in an icy rut. Different solutions to different problems.

[c0nsumer]

FWIW, in Michigan studded tires are illegal for on-road use in the Lower Peninsula. But they are legal in the Upper Peninsula.

That said, I strongly disagree with you about AWD. It makes a tremendous difference for control in general in all winter conditions. Adding snow tires to AWD and things are just excellent and way more predictable.

[Gwypaas]

AWD really does nothing, it helps with acceleration but that is the easy part. The hard part is slowing down and all cars brake using all 4 wheels.

You don't brake better with an AWD car.

Well, except if you have learned to drive using 4 wheel slides like a rally driver. Then I sincerely hope you lose your license before your endangerment of others lead to an accident.

[ynniv]

I used to drive a RWD BMW in the snow, and it seems lost on people that all cars have four wheel braking. All you need are decent snow tires.

[c0nsumer]

> You don't brake better with an AWD car.

You engine brake better with an AWD car.

[Gwypaas]

Even better with ABS brakes. You should never be that close to the limit, either way. Then you are already driving dangerously.