It’s getting to be that time of year when snow, frost, sleet, blizzard conditions, flurries, freezing rain, slush, ice, and “wintery mix” (See also: How many words for snow do the Eskimos have?) make driving even more hazardous than it was before.
The tires on your car are the single most important element in winter driving. They’re the interface between the vehicle and the road. The friction at that interface is what makes the car move, stop moving, and changes the direction of its movement. The more effective the friction, the better off you are.
The first thing you should know is that “all weather” tires aren’t. They’re actually all-weather-except-snow tires.
Snow tires have tread patterns and are made of rubber compositions that are markedly different from all-weather tires. Your all-weather tires are optimized for increased gas mileage. Your snow tires are maximized for friction.
Which reminds me of a joke: A couple of guys die and go up to heaven. Saint Peter meets them at the gate and says, “We’re renovating right now and your rooms aren’t quite ready. So you’ll get six more months on Earth, and you can be anything there that you want to be.”
The first man says, “I want to be a glorious golden eagle, soaring above majestic scenery,” and Poof! he’s gone. The second man says, “I want to be a real cool stud,” and Poof! he’s gone too.
Six months pass, and St. Peter calls an angel to go get the two guys. Peter says to the angel, “The first one will be easy: he’s an eagle at the Grand Canyon. The second one will be a challenge. He’s on a snow tire somewhere in Detroit.”
So, if your local jurisdiction allows it, consider studded snow tires. They really work (though the sound when you’re driving on dry pavement can be annoying). If you don’t have studded tires, or if you do, (or if you’re going to go with those all-weather specials), pick up a set of chains to keep in the trunk, and practice putting them on.
There are three kinds of friction failure that your tires can suffer. One is failure in a straight line: failure of acceleration. If the tires spin you don’t go forward. (Note: if you’re spinning your wheels, stop right now. All you’re doing is digging yourself in deeper, and making the hole you’re digging smoother and slipperier.) You can do this on dry pavement too: “smoking” your tires
Failure of braking is also a straight-line failure. That’s when you put on the brakes and keep going anyway. You can see that on dry pavement, when you get skid marks on the highway. Note: skid marks are straight. The curved marks that many people call “skid marks” are actually yaw marks, and are caused by a failure of steering.
If you find yourself skidding, take your foot off the brake and allow the vehicle to coast. Continued braking can turn a skid into a yaw, and the world will turn to dung before your eyes.
The third failure is failure of steering. Normally when you turn the wheel the front wheels turn to left or right. Wheels roll perpendicular to their axes; there’s less friction to overcome if the mass of the auto goes in that direction too. But what if the friction of the road surface is diminished? You crank over the wheel and the difference in friction isn’t enough to overcome the momentum that’s making your car tend to move in a straight line. Well, you continue in a straight line too. As you plow ahead the front end of the vehicle slows while the rear end continues at speed: the whole vehicle starts to rotate around its vertical axis and you lose any say in where your car will end up. Someplace soft would be nice. Into a tree, or into oncoming traffic, is a bit less nice.
Here’s far more on how to recover from the situation when the rear wheels aren’t following the front ones: Know How To Recover From a Skid.
Note too that if your brakes don’t exactly slow your tires at the same rate, the rear of the car will tend to rotate. Flat spins aren’t much fun. The best way to recover from a spin is not to get into one. Slow down.
(Sometimes, whilst driving around in the ambulance, some Jehu passes us. We wave cheerfully and say, “See you later!” Often enough, we do….)
Many American two-wheel-drive vehicles are actually one-wheel drive. One front wheel or one rear wheel. That too is a source of unbalanced forces that can lead to spinning out.
“How about four-wheel drive?” I can hear you ask. Four-wheel drive is great, but can get you going too fast for conditions and provide unwarranted confidence. Remember that all cars are four-wheel-drive when they’re braking.
Now to the driving itself: Slow the heck down. For guidelines, in a storm, on an Interstate, pretend that the speed limit is 45 MPH regardless of what the signs say. On a US or state highway, 40 MPH. On rural or lightly-traveled roads, 35 MPH. Be ready to go slower. All the way down to zero. (In whiteout conditions, get off the road and turn off your lights so the clown who’s following your lights doesn’t rear-end you.)
Ask yourself: is this trip really necessary? Be realistic. Be ready to pull over and stop at a motel if things look too hairy. Don’t only think of your own car and skill: Think of the cars and skills of the other lunatics who are out there in the middle of a winter storm.
Okay, let’s say that it’s really necessary to go, you’ve got winter tires, you’ve got chains, and you head out for the highway. Call 511 (in the USA) for travel information. Stay updated.
Drive slowly. Better late than never and all that. Leave lots of space around your car—three car lengths or more if you can. Accelerate slowly, brake slowly, and do not even consider using Cruise Control. Try to limit your travel to daylight hours. Give highway maintenance and emergency vehicles a wide berth.
Keep positive control of the wheel at all times. When you’re coming out of a turn it’s easy to just let go and let the front tires straighten themselves while the wheel slips through both your fists. In winter that can kill you. Black ice happens. For most turning, you don’t need to switch hand position at all. For larger turns, here’s how to do it: For example, in a left turn, loosen your grip with your left hand while still keeping it around the wheel. Move the right hand toward the left, with the wheel sliding through the left fist. When your hands come together, clamp down with your left hand, loosen the right, and slide it back over to the right. You may need to repeat the movement several times for a very large turn. Practice this during good weather so that it becomes natural and habitual for you.
You know those signs that say “Bridge freezes before pavement”? Believe them. Other places to watch out for ice: where a single tree shades the road while all around is sunny and bright, in a road cut with a bare rock face, and everywhere else.
“What should I keep in the trunk of my car other than those chains?” you ask. A tow strap, a sleeping bag, some of those orange-reflective safety triangles or a set of flares, and a big bag of sand. Not your smooth sandbox sand, your rougher beach sand. (Strips of carpet also work.) An extra gallon of windshield fluid. A container of “dry gas.” A flashlight. Batteries for that flashlight. A folding shovel. A windshield brush/scraper. Consider spare clothing/hat/boots.
Back when I was a Cub Scout Leader we used to make car kits in a single tin cup. The kits had:
In a tin cup:
The cup with its contents fit into a sandwich-sized Baggie. The entire thing went into the glove box, where it could be ignored until needed.
Here’s Field and Stream’s Altoids-tin survival kit, which can similarly be put together, put in the glove compartment, and left until needed.
All else is commentary.
#27 ::: Diatryma ::: (view all by) ::: November 01, 2007, 08:49 AM:
This was a year ago, but it’s certainly appropriate: