The dollar theory of driver attention, and winter tires

"Seat Safety Switch" (seat-safety-switch) 11/20/2013 at 12:30 • Filed to: None

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So it's snowing pretty heavily where I am. It snows every year, a lot, around the same time. Somehow there are still a lot of people who think AWD is a sufficient replacement for having snow tires, and just "being careful" is enough to get them through the eight-month-long season without a car accident.

Here is my response.

You guys are familiar with the dollar theory of traction right? It basically says, if you have only so much traction to spend (a dollar), when you take a corner you can distribute that traction between turning, braking and accelerating. When you overspend on either, you either end up in understeer or oversteer conditions. Taking an autocross school will learn you up on this theory.

I have sort of a similar theory about driving in general in that you presumably only have a dollar to spend on not having a horrible accident.

Most people are probably at 60 to 70% of their driving ability going down a straight dry road in the sun with a properly equipped car, paying full attention. They're spending 60 to 70¢ of that dollar.

Throw a cell phone into the mix and those people are running at 80-85¢. Maybe some snow and they're into the early 90s (a conservative estimate judging from how well the locals seem to deal with it) because they have to pay more attention to driving and use more of their ability. Maybe they're tired because of DST changes or their car isn't prepared properly in some other way (bad brakes, spotty alignment, foggy windshield) or their job is experiencing layoffs and they haven't had enough sex with the boss because he has some weird hairy mole on his inner thigh and it's grossing them out just thinking about it and they aren't really checking their rear view mirrors periodically anymore. Now we're at 95¢.

If something suddenly happens they can be overdrawn on that "ability dollar" and that's where you get an accident.

If adding winter tires to that mix reduces their steady state spending to even 80¢ with all these other factors going on, the chance of them having an accident when something suddenly happens (black ice, someone cuts you off, equipment failure) drops precipitously.

It's not like winter tires are magical devices to actively prevent accidents if you're paying attention; anyone could presumably complete a commute on R-compound tires in the snow as long as they're willing to get stuck and go incredibly slowly. The thing is that they allow you to reduce your base spending of attention/focus/driving ability in the steady state so if anything goes wrong (which we all have frightening stories of) there's more of a chance of coming out the other side.

You guys are familiar with this concept. I could drive to work in a 1970s domestic sedan with funky weight distribution and corded tires but I have to spend way more attention driving it and won't have as much opportunity to react to something going wrong.

Then again, you could also just get them so you don't look like the frickin' putz out behind my place who just polishes the snow with his Mini instead of buying winter tires or driving around the block to go up a slightly less steep hill.

Laird Andrew Neby Bradleigh > Seat Safety Switch 11/20/2013 at 12:41

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That was a rather long read mate. I usually tell people that "You've got this thing called momentum, in a car you usually have forward momentum. AWD and 4WD will help you get that, but it sure won't help you REDUCE that when you abruptly need to come to a halt, awd/4wd means four wheels help you go forwards, but you've ALWAYS got 4 wheels making you stop, on slippery tyres awd won't do shit"

drmindbender1 > Seat Safety Switch 11/20/2013 at 13:06

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Overconfidence is also part of the mix. Hand an average person anything with AWD or 4WD and they will act like Patton crossing Africa when it snows outside. Never mind the fact that a modern SUV is 5000lbs of flabby whale shit that will still slide around, especially since it probably has "hybrid" off road tires (or maybe even regular P tires). Having proper rubber is paramount to safety.

Towing guys have literally thousands of stories about this.

Simplecar > Seat Safety Switch 11/24/2013 at 02:59

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A very well written article explaining one of the most basic things we often forget.