Tips on Driving in Subzero Temperatures

by Jerry Romick Google

    Winter weather brings unique hazards to drivers. Snow and ice make starting, accelerating and steering challenging -- and when temperatures dip below zero, weather-related hazards can be magnified. The extreme cold can negatively affect your car's performance, causing fluids to thicken and your battery to function improperly. If you must drive in such conditions, there are a number of things, both preventative and while on the road, you can do to help ensure you reach your destination safely.

    Snow Tires vs. All-Season Tires

    Your car's tires play a crucial role in safely driving in subzero temperatures. Snow tires provide superior traction on snow and ice, and respond more favorably to subzero temperatures than all-season tires.
    All-season tires were introduced by Goodyear in 1977 with the debut of the company's Tiempo tire. Since then nearly all new cars sold in the United States come equipped with all-season tires. Designed to handle a wide range of weather conditions, all-season tires lack the more aggressive tread design of snow tires and are made of rubber compounds that don't remain as flexible as those used in snow tires when exposed to subzero temperatures.
    A head-to-head test at the Automotive Enviro Testing center in Baudette, Minnesota, pitted Goodyear snow tires against a set of Goodyear all-season tires on two 2011 Chevy Equinox models, one with all-wheel drive and the other equipped with front wheel drive. On packed snow and ice the snow tires significantly outperformed the all-season tires in accelerating from 0 to 60 mph, braking from 60 to 0 mph, cornering and climbing a 10-percent grade.
    For drivers in areas with frequent heavy snow or icing, snow tires present the safest alternative for subzero driving conditions. It might be tempting to install only two snow tires, on the front wheels of a front-wheel-drive vehicle for example, but doing that can lead to unpredictable handling. While a set of tires for winter and another for summer may seem cost-prohibitive, it will extends the life of both sets, since neither is being used year-round. Regardless of what type of tire you use on your car, be sure to regularly check the tire pressure since it can drop by up to 1 psi for every 10-degree drop in temperature.

    Recovering From a Skid

    Road surfaces can be deceptively slick in subzero temperatures. Snow and ice rob your car of traction, and often you won't notice ice until you're spinning out on it. The best way to avoid a skid is to drive slower than normal and avoid sudden changes in speed or direction. Posted speed limits are meant for ideal road conditions.
    The two basic types of skid are the rear-wheel skid, often called oversteer or fishtailing, and the front-wheel skid or understeer. Fishtailing often occurs when a car is going too fast in a curve; during sudden braking or acceleration, or when a jerk of the steering wheel causes the wheels to break traction. In some cars, entering a curve with excessive speed, with our without sudden braking, will cause an understeer -- the car will essentially plow forward despite the angle of the turned front wheels.
    Your reaction to fishtailing will be based on your car's drive system. In a rear-wheel-drive car, stop accelerating and don't slam on the brake. If you have started braking, gradually release the brakes and turn the steering wheel in the direction you want to go. As the car begins to correct you may need to adjust the steering wheel slightly in the other direction to maintain control. If your car is a front- or all-wheel-drive vehicle, the sudden release of the accelerator will likely increase the skid as the front wheels slow faster than the rear wheels. In this situation, apply slight acceleration to allow the front wheels to pull you out of the skid. If your speed is too fast to use this method, try pushing in the clutch if you have a manual transmission or putting the car in neutral if the car's an automatic so the front wheels will match speed with the rear wheels, and steer in the direction you want to the car to go. To correct an understeer skid, gradually apply brake pressure while turning the steering wheel slightly toward the direction of the skid, to allow the front wheels to regain traction.

    Braking In Subzero Temperatures

    Slow and steady is the key to driving in subzero conditions, especially in the presence of snow and ice: When the roads are slick you'll need more time to get your car to a complete stop. If your car is equipped with anti-lock brakes you'll want to apply firm continuous pressure when braking -- don't pump them. Your ABS allows you to steer while braking by preventing the wheels from locking up. On a car not equipped with ABS you should gently apply pressure to the brake pedal to begin slowing your car, then release some pressure so as not to induce a skid, and then apply pressure again to bring the car to a gradual stop. For this method to be effective you have to give yourself enough time to stop, so begin braking as early as possible. Keep all inputs and transitions smooth and gradual.

    Keep Snow and Ice Off Your Car

    Before heading out on the road you should clear as much snow and ice off your car as possible. This will keep snow from sliding off the roof of the car and obscuring your view through the windshield. Ice and snow can accumulate on the undercarriage and in the wheel wells and wheel covers on your car. Not only can this negatively affect your car's handling, it can cause damage to brake lines and cause fluids to freeze. Be careful when removing this ice and snow so as not to damage parts or the paint job.

    Cold Air Effects

    Because cold air is denser than hot air it doesn't flow as efficiently through your car's air filter, especially if the filter is dirty. This can negatively affect the fuel consumption and overall performance of your vehicle. A fresh air filter will negate that issue.
    The cold air flowing through your car's grille when you're driving can make it harder for the cooling system to operate effectively. You can cut some of that subzero air flow by covering a portion of the grille with a padded cover made specifically for that purpose, or simply by cutting and inserting a section of cardboard.

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