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11 tips to help you get where you’re going, and get there safely. (Reprinted with permission from AMI AUTO WORLD magazine, 1/30/01) When the road is smooth and dry, even the greenest driver can accelerate, steer, and stop with a reasonable expectation that the car will respond in exactly the way the driver intends. But when the weather turns cold and nasty, it’s a whole different game—one that requires preparation and a thorough understanding of how a car reacts to acceleration, deceleration, stops and turns on slippery surfaces. Once you gain that understanding of what the car is doing, it becomes almost second nature to make steering and throttle corrections that will allow you to maintain control. Here’s a guide, prepared with the help of several winter-driving experts, that explains those vehicle dynamics to help you to improve you winter-driving skills.
Finding the correct driving position is critical in winter because your split second decisions depend in great part on your feeling what the car is doing. Before you start the engine, adjust the seat so that your wrists can rest on top of the steering wheel while your arms are just slightly bent. Buckling your seatbelt to a snug but comfortable position will keep your body in better contact with the movements of the car. You’ll have a far better chance of reacting to a loss of tire grip and the start of a skid if you feel the subtle movements of the car under you. Steer with your hands at the 9 o’clock and 3 o’clock positions. As you turn the wheel, don’t allow either hand to go past 12 o’clock. Once either hand goes beyond 12 o’clock, it becomes much more difficult to feel the steering or to make the subtle adjustments needed to control the car.
If there is one thing that never changes in winter driving, it’s that conditions are always changing. The secret to winter driving is to adjust your speed to best handle any conditions. The road you traveled a few hours ago, when the temperature was below zero, is a far different surface when the temperature reaches 32 degrees. Snow melting in the heat of the sun, followed by a drop in temperature, can turn a road into a sheet of ice in less than hour. Use your radio to monitor the weather, and don’t be too proud to pull off the road if conditions become dangerous. “Many drivers overestimate their skills on snow and ice,” says Mark A. Cox director of the Bridgestone Winter Driving School in Steamboat Springs, Colorado. Test the surface as you travel along on a straight stretch by lightly tapping the brakes or making tiny steering changes so you will know what to expect if you suddenly need to brake or steer quickly. Don’t make the mistake of believing that anti-lock brakes, traction control, or four-wheel drive makes you immune to the perils of a skid. When it comes to safety, technology can help, but common sense is more important than computer circuitry. TIRE GRIP
In good weather, all season tires are fine, their treaded surfaces whisk water away to help your vehicle maintain its grip on the road. On snow-covered roads, however, the special rubber compounds and tread patterns of true winter tires are much more effective. And it’s best to mount winter tires on all four wheels. Goodyear Tire & Rubber Company expert Bob Toth says, “To optimize handling, stability, and traction, four winter tires are definitely better than two. Winter-tire tread designs, regardless of construction, produce different handling characteristics than all-season tread patterns. Those differences can affect the handling and traction of the vehicle.” Goodyear, for instance, claims its silica-based Ultra Grip Ice tire delivers up to 35 percent better snow traction and up to 40 percent better ice traction than conventional all-season tires.
WEIGHT DISTRIBUTION When you drive on slippery surfaces, you need to react almost instinctively to the changes in weight distribution that are a result of your actions. Acceleration causes the front of the car to rise, transferring some of the weight from the front wheels to the rear wheels. The result is better traction for the rear wheels, which mean your car will tend to continue in the direction it’s headed; on snow or ice, it may not respond well to steering-wheel movements. Deceleration, on the other hand, causes a weight shift to the front wheel and provides increased traction for them; the result is that your car will be relatively more responsive to steering-wheel movements.
By learning to control these weight shifts, you can create greater or lesser traction on the front or rear wheels to assist you in maintaining—or regaining—control. Empty, snow-covered parking lots are good places to practice these techniques at low speeds. ROAD CAMBER The camber—or banking—of the road makes an enormous difference in how well you can negotiate a curve. If the grip of the tires is lost, a vehicle will change direction depending on that camber. On a curve that is banked like a racetrack, with the low side on the inside, traction will be much better than on a level surface. If the curve is level, you need to reduce your speed, because your momentum will pull the car toward the outside more strongly. The nightmare curve is the one that is banked in the opposite manner, with the outside lower than the inside; it seems as if the curve were actually trying to throw you off the road. The key to safely negotiating any slippery curve is to reduce the speed of the vehicle so that—given the conditions—you maintain maximum traction.
WHEELSPIN / LOCKUP When each revolution of a wheel is equal to the distance traveled, the tire is said to have 100 percent grip. When a revolution of the wheel is greater than the distance traveled, the condition is known as wheelspin. Conversely, wheel lockup occurs when the revolution of the wheel is less than the distance traveled. The point of this vocabulary lesson is that when wheels spin or lock up, you are out of control. Wheelspin is generally caused by too much power at the driving wheels. Easing up on the gas pedal is the best way to regain traction. Lockup occurs when excessive braking is applied on a slippery surface, and it’s harder to recover from the wheelspin. The only sure way to regain grip after lockup is to release the brake and allow the car to stabilize, and that requires both time and distance. CADENCE BRAKING Stopping smoothly and gently is the best way to keep from locking up the wheels. That requires looking far down the road and anticipating the need for braking. “Threshold braking” is the technique of applying just enough pressure on the brake pedal to slow the car without triggering a lock-up and a skid. If the brakes do lock up, the way to regain control is “cadence braking”: precise, on-and-off pumping of the brake pedal to allow the wheels to rotate long enough to control direction and stop long enough to slow the car. If your vehicle is equipped with anti-lock brakes (ABS), the system will automatically perform cadence slipping or locking up. Don’t pump the brake pedal on a car equipped with ABS, or you’ll defeat the action of the system.
In his textbook for racing drivers, Going Faster, Skip Barber Racing School instructor Carl Lopez defines understeer this way: “If you were [rounding a corner] with a car which reached 100 percent of the tires’ cornering capabilities at the front tires before the rears, the front end of the car would slide first, leading you nose-first away from the direction the front wheels were pointing. Understeer is most likely to happen when the driver enters a turn at too high a rate of speed or brakes in the middle of the turn When you’re turning on a slippery road, your foot should be off both the brake and the accelerator. Adjust your speed before you reach the turn, and coast through with smooth, conservative steering. Once you have nearly completed the turn and are returning to straight ahead, accelerate gently.
OVERSTEER
ANTICIPATION
OVERTAKING
In the process of overtaking the car ahead, you risk doing all of the things that contribute to wheelspin, wheel lockup, and loss of grip. Do the math. If the vehicle in front of you is doing 50 mph, and you’d rather do 55 mph, passing it will gain you only 33 seconds over the next 5 miles. Before you overtake another vehicle, it’s wise to ask yourself: Is it worth it?
BEFORE YOU SET OUT Here are some things you should do before you venture out for a drive on snow and ice. *Dress warmly. You should have enough clothing with you to keep warm if you slide into a ditch and have to leave the car. However, don’t wear bulky clothes and heave boots while driving. *Clear any snow or ice that has accumulated on the car. *Plan the route you will take, and try to avoid hills and bad roads. *Try to drive in daylight hours. *Install winter wiper blades. *Wear good sunglasses to reduce the glare of sunlight reflecting off snow. *Make up an emergency kit that includes a shovel (for digging out of snowbanks), non-perishable food and drinks, flares, a flashlight, a tow rope, a bag of sand, a thermal blanket, matches, candles, and other items you might need should you become stranded. *Carry a cellphone. |
DRIVING
POSITION 
CHANGING
CONDITIONS 
If you
examine the tires on an Indy racing car, you will see they are absolutely
smooth, without a trace of tread. Those “slicks” work well on a dry track,
but after just a few drops of rain they lose virtually all traction.
Before that can happen, the cars return to the pits and switch to treaded
“rain tires.” Street cars can’t make 20-second pit stops to change tires
when conditions change, so you should change yours weeks in advance of
winter weather. 
It’s
important to know if the tire you’re considering is a true winter tire.
Recently, the tire industry established standards for snow-tire
performance. Tires meeting a certain tractive-performance rating on snow
can be marked with a “mountain/snowflake” symbol. Such tires are expressly
designed for snow and ice. 
UNDERSTEER
The
opposite condition is—logically enough—oversteer. Lopez says oversteer
occurs when “the rear tires reach the limit first and slide out wider than
you intended.” The tail end of the car swings out, chase-movie style. As
with understeer, the most common cause of oversteer is excessive peed when
entering a turn. Once oversteer begins, however, slowing down may cause a
weight transfer from the rear wheels to the front wheels, which only
further reduces the rear wheels’ grip. This is where being able to feel
the car pays off. As you feel the rear end starting to spin out, gently
accelerate to transfer the weight back to the rear wheels. At this point,
it is critical that you do not panic and steer wildly. Steer in the same
direction the rear end is sliding. Look down the road in the direction you
want the car to go. Oversteer most commonly occurs in front-wheel-drive
vehicles, but rear wheel-drive cars may oversteer when the rear wheels
spin. In this case, feather the gas pedal until you feel the wheels grab.
Keep
in mind that maintaining maximum traction is the key to driving on snow
and ice. Driving straight down a level Interstate is one thing; it’s when
you need to turn that the grip factor becomes critical. The sharper a
curve, the more grip you need to maintain control. Anticipating the curve
by reducing your speed before you get to it is the best thing you can do
to maintain traction. Mark Cox says, “One of the most common mistakes is
starting to turn too early with a minimal steering angle. Ass the car
moves through the turn, the driver is forced to steer more. If the speed
is a little too fast, understeer can be the result, with little room to
correct before crossing the center or going off the road.” 
While
learning the techniques we’ve discussed will improve your winter driving,
we want to stress that common sense is your most important asset. That is
particularly true for passing situations. Realize that passing another
vehicle on a snow-or ice-covered highway is probably the most dangerous
maneuver in winter driving. Think carefully about it before attempting any
pass.