7 things you need to know about winter driving

Fender bender alert: Winter driving season is here and knowing the science may keep you safer on the snow and ice

The snow and ice of winter are here.  Being prepared can keep you safe and save you from costly auto-body and towing fees.  Even those of us who are winter driving "experts" need a brush-up on the physics of driving in the snow: the science of what happens when we hit the brakes and how to keep tires gripping the road.

"Winter driving doesn't necessarily involve snow and ice," says Kurt Spitzner of the Bridgestone Winter Driving School and Bridgestone Winter tire test driver.  Winter driving starts at 45 degrees Fahrenheit.

1. Consider winter tires.

"The rule of thumb from the tire manufacturers is that if you walk out the door of your house in the morning, and you can see your breath, you probably need to have winter tires on your car," reports Spitzner.  

All-season tires are made from rubber that starts to harden around 45 degrees F. We all know how fast hard plastic sleds can go in the snow.  Winter tires are designed with rubber that stays flexible down to 20 degrees below zero.

While renting a car for a snowy vacation, check out the tires' ratings – look for the mountain-snowflake icon and "M+S" on the tire.  And check local laws about carrying traction chains.

2. Don't rely on your All-Wheel-Drive (AWD) to keep you safe

Spitzner explains the school tested braking distances between four-wheel-drive and two-wheel-drive SUVs; all had Winter tires. "The two-wheel-drive SUV could actually stop shorter because it weighed less." The added mechanics added more mass/weight to the vehicle. 

AWD does help you accelerate, "The all-wheel-drive car will accelerate from that stoplight faster." There is more tire gripping the road. But, it won't help you corner or stop. He would drive a front-wheel-drive car in Colorado all winter if you were wondering.

3. Don't rely on your car's Antilock Braking System (ABS) and traction control to keep you safe.

"Think of traction control or anti-lock brakes as thinking of yourself as a trapeze artist, and those two systems are your safety net. If you're a trapeze artist at the circus, a good trapeze artist isn't bouncing off of their safety net all the time," Spitzner says.

He explains the science behind these safety features on cars that are the opposite of each other.

ABS – When you jam on your brake, the ABS senses when a tire slips and releases that brake. "Your car is making that decision hundreds of times per second," says Spitzner. "That's what gives you that vibrating feeling on your foot when you're in a panic stop because what the ABS is doing is trying to send the most hydraulic pressure it can to whatever corner of the car has the best grip."

Traction Control – This system applies brakes to a wheel that is slipping while accelerating in the opposite way ABS releases the brake on a wheel.

Use the safety net in an emergency but try to stay on the trapeze by using the following few tips. 

4. No multitasking; only ask your car to do one thing at a time.  

Accelerating, braking, and turning deserve 100% effort when road conditions are less than 100%. "If you're telling the car to do two things at a time, like braking and steering, you are compromising either of those things from happening well."

Brake gently, well before a turn when the car is still going straight.  Once you've slowed, take your foot off the brake and turn the wheel.  When the wheel is straight again, accelerate.

5. Pre-adjust your speed. 

Look down the road as far as possible, so you can see turns, cars, or anything else on the roadway ahead of time so you can apply the brakes gently or downshift.  Think pre-adjusting instead of reacting to turns and stops.

Sit back and look up Spitzner says, "I tell my students, if you feel yourself creeping up on the steering wheel, you know where your hands are only inches away from your face, and you're trying to peer off the edge of your hood. You're already in trouble."

6. Use your preventive measures before you get into an oversteer or understeer skid.  

We have all been told to "steer into a skid," but what does that mean?  Spitzner said steering into a skid only solves oversteering. When you oversteer, the back end of the car comes around. "Most people, almost immediately, do the right thing, which is, if you were trying to turn into a right-hand turn and the back end of the car started to go out to the left, you will automatically turn the steering wheel a bit to the left to try to catch the car."

Take the same right turn, but the car continues straight even though the wheel is turned.  This is understeering and is much more common. He says, "Unfortunately, the initial response for a typical driver is to say, 'Oh, I must not have turned the wheel enough,' and they crank it more, which only makes this get worse. It makes the car plow forward."

Correcting takes practice.  Take your foot off the accelerator and straighten the wheel to get the tires rolling in the same direction of the car again.  Apply brakes gently. 

As an instructor, Spitzner says, "While I can teach you how to get out of an understeer skid, the reality is what we need to do is teach you not to get in the skid in the first place."

7. Downshifting is an option. 

Let your engine slow the car down itself by downshifting to a lower speed/gear before a hill or turn.

"What it does is that you're using that lower gear as the primary means of managing your speed, and then you can just use your brakes to adjust your speed gently," says Spitzner, who recommends peeking in your owner's manual to check speed ranges for each gear.

Myths

Remember when your dad told you to weigh down the car with kitty litter?  We don't have to do that anymore.  Spitzner says that modern cars are better balanced now.  Even pickups have the balance of most conventional cars.  He says you can use the kitty litter for traction under your tires, though.  Floor mats and branches also work to create more grip if you get stuck just off the road.

And he says, don't rock the car, alternating between forward and reverse, to rock your car out of a slippery spot or ditch. "There are a surprising number of manufacturers of automobiles now that no longer allow you to do that with an automatic transmission. Because it's a great way to blow up the transmission."

If you slide off the road …

If you think you can get safely and efficiently back on the road, try stuffing floor mats or branches under the tires – anything that will give you a little extra traction. 

If you can't get yourself out quickly, call the police or roadside assistance.  Spitzer says, "Consider your surroundings and what is safe for you. Stay warm and hydrated and a little bit fed.  If you're down 25 feet in a ditch, you need to be focusing on how are you going to survive that and not how are you going to get the car back out."

TRAVELING THIS WINTER? HERE'S WHAT TO KEEP IN YOUR CAR IN CASE YOU GET STUCK.

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