[sunshinesnacks]

> AWD doesn't help you stop in bad weather

I frequently think about this when weather gets bad! I already have AWB (all wheel braking?). Seems like AWD could make it too easy to get in a situation where my AWB isn’t sufficient to stop

[cucumber3732842]

>Seems like AWD could make it too easy to get in a situation where my AWB isn’t sufficient to stop

It's the opposite. You're more likely to carry too much speed into a situation in a FWD/RWD vehicle because doing so improves things a lot of the time. Take for example a highway merge. You can't accelerate well, so you carry more speed through the turn to make the merge more safe. Well that works great and improves safety for all until some moron stops at the end of the ramp. With the AWD vehicle you can come into that situation and many, many more with less speed.

Acceleration is the weakest link in the snow. The sketch factor goes way down once you get AWD. This is why no matter how hard the internet screeches about snow tires the median consumer who drives in a fair bit of snow will choose AWD first.

[wat10000]

That's never been the case for me. Acceleration may be the issue I'm most likely to encounter, but the worst thing it'll do is inconvenience me. If traction is bad to the point where I won't be able to accelerate properly on a ramp, then either everybody's going slow enough that it doesn't matter, or I'm going to stay off the highway because it's too dangerous.

Trouble accelerating in snow is common and a non-issue. Trouble stopping is uncommon but a potential disaster.

[cucumber3732842]

It's not the highway that gets you (typically). It's all the stupid little roads that are built to substantially lesser standards. Steeper grades, tighter curve, hard 90 junctions, etc, etc.

You carry just a hair too much speed into a curve because you're anticipating not wanting to have to use any gas pedal on the rise just beyond and you wind up in the ditch. Or you go wide into a curb because you took a less optimal gap in traffic at a ~5 roll when taking a left turn because that way makes you less likely to get T-boned than coming to a stop and trying to find an even bigger gap in traffic. Or you slide backwards down some stupid driveway or bump something in a parking lot (ask any delivery, parking lots and driveways are the worst).

[wat10000]

Sounds like a skill issue, as the kids say. If you go too fast, you'll be sad. I don't buy it that 2WD makes you more likely to go fast.

[saalweachter]

Snow tires, people! Snow tires!

A FWD vehicle with snow tires is frequently better in the snow than an AWD without snow tires. Better control, better stopping, better uphill on snowy roads.

[cucumber3732842]

>A FWD vehicle with snow tires is frequently better in the snow than an AWD without snow tires. Better control, better stopping, better uphill on snowy roads.

Control and stopping of course, but I'd love to see the justification behind "better uphill"

Napkin math says that doubling the contact patch over which the motive force applies still wins because snow tires aren't going to double your friction coefficient. And this is before you consider unloading of the front suspension on a hill (though for most grades it's still probably got more weight than the rear of RWD).

Furthermore, this seems to be corroborated by reality. People in snowy climates tend to go AWD rather than snow tires and snow tire makers typically advertise by comparing stopping/handling rather than acceleration.

[saalweachter]

Snow tires can actually double your coefficient of friction on snowy pavement!

The coefficient of friction drops fast on snowy ground, with all season dropping as low as 1/3-1/4 of their dry value.

Of course, snow tires plus AWD is even better, but I find snow tires on a FWD vehicle to be plenty to drive up steep hills in snowy weather. (Before learning of the wonders of snow tires, I used to have to take different routes home if it began snowing because I couldn't reliably make it uphill without losing traction.)

[cucumber3732842]

>Snow tires can actually double your coefficient of friction on snowy pavement!

Citation? Seems to good to be true. Maybe studded tires on the perfect ice.

>The coefficient of friction drops fast on snowy ground,

NickCageYouDontSay.jpg

[vablings]

https://www.edmunds.com/car-reviews/features/tire-test-all-s...

It's likely more than double as the test results indicates lateral G not coefficient of friction. Snow tires make a bigger difference than any other factor. Good tires make a bigger difference on track too, more than any one single performance upgrade

[cucumber3732842]

That's vs the summer tires. Compared to the all seasons the results are much more modest and square with observed reality rather than internet hype.

From the link:

>Snow Test Results >No one expects the snow tires to come in anywhere but 1st place >on this wintry surface at AET. The point here is to see how big their advantage really is over all-season and summer tires.

>It takes 11.7 seconds for our Civic Si to accelerate to 40 mph on snow tires, and 14.5 seconds to get there on all-season rubber — nearly 3 seconds and 24 percent slower. As for the summer tires, well, they require, ahem, 41.7 seconds as they struggle to 40 mph. That's no typo; it takes a half-minute longer — 257 percent more time — for the summer tires to reach this modest speed.

>What about our traditional 0-60-mph test? Well, snow tires get to 60 mph in 19.1 seconds, while the all-season treads arrive in 22.9 seconds, nearly 4 seconds later. Forget the summer tires, however. The available 3,650 feet of snow — seven-tenths of a mile — isn't enough. We figure 67 seconds and 3,100 feet are needed to get there, and then there's the small matter of needing to stop again.

>And that brings us to our next test: full stops with ABS engaged. Here again the snow tires dominate, stopping from 40 mph in 156 feet, some 28 feet shorter than the all-season tires' 184-foot performance. Meanwhile, our summer tires skate to an ultimate distance of 351 feet, the ABS actuator rattling for all it's worth the whole way.

>Increase the starting speed to 60 mph and these distances more than double. It takes 362 feet for the snow tires to stop and 421 feet for the all-season donuts. The summer tires sit this one out because they can't manage to get themselves to 60 mph in the first place. (We do the math instead and come up with an estimate north of 800 feet.)

>Skid pad results follow the same now-predictable pattern. Our snow tires pull 0.30 lateral g, the all-seasons manage 0.28g and the summer tires produce a pitiful 0.15g despite a heroic effort by our shivering hot shoe.

[saalweachter]

I would note the big difference in that trial is for summer vs snow, with all-season showing smaller degradation.

So there's two things going on: first, snow tires are a softer rubber that functions better at lower temperatures. There is a zone of "warm" snowy weather where all seasons are just fine, but then you get below 20F or 15F or so, and the all season start to harden, and their performance drops off a cliff.

Second, snow tires are made to get packed with snow at low speeds, because the friction of snow on snow is higher than snow on rubber.

So damn cold weather or enough snow for the packing to kick in, and two snow tires will start beating four all season.

[mingus88]

Yep

All cars are “all wheel stop”

All wheel drive doesn’t matter when you lose traction and need to stop. When you are sliding on ice all cars perform the same, and the quality of your tires is what matters. AWD just gives people false confidence to drive faster than they can stop.

I convinced my wife to stop buying the absolute cheapest tires by telling her it is literally the only part of the car that actually touches the road. Why would you cheap out on that?

[dghlsakjg]

Yup. Growing up in Colorado you realize that AWD is frequently the cause of the trouble in bad weather rather than the solution.