If you have to drive on snowy and icy roads in winter, you know how quickly your car can lose traction. At best you'll simply spin your wheels momentarily while your vehicle hunts for grip. With less luck, you could suddenly find yourself hopelessly stuck or, worse, spinning out of control into a roadside ditch.
All- and four-wheel drive, traction control, and winter tires can give your vehicle added grip in slippery conditions, which adds an extra margin of safety and control. But you should know their advantages and limitations.
Most vehicles are two-wheel drive, which means that only the front or rear wheels get power. Vehicles that have AWD or 4WD can power all four wheels. So if the rear wheels are slipping, the front ones can often pull you through. Or vice versa.
That's why AWD is usually fine for driving in light to moderate snow. Automakers often use "AWD" and "4WD" interchangeably in ads and badging. But true 4WD provides low-range gearing, which helps in serious off-road conditions. Look for an automatic or full-time system, which can be used on all surfaces. Part-time 4WD requires you to switch modes manually, and the car shouldn't be driven in 4WD on dry pavement.
Vehicles with AWD and 4WD generally cost more than their two-wheel-drive counterparts. With their extra weight and components, those systems also can reduce gas mileage by 1 mpg or more.
A lot of drivers get in trouble because they think that AWD or 4WD lets them go as fast as they want on slippery roads. In fact, although the systems provide maximum traction when traveling straight ahead, they provide no added benefit when braking or cornering. For aid when braking, make sure you have an antilock braking system; for cornering, you need electronic stability control.
Traction control helps maximize grip by limiting how much the drive wheels can slip. It does that by rapidly and strategically applying the brake of a slipping wheel, which shifts traction to the opposite one, and sometimes by cutting engine power or upshifting the transmission to minimize wheel spin.
It's not as effective as AWD or 4WD. If no drive wheel has sufficient grip, such as on a slick incline, traction control might not help and could bring you to a standstill. In such cases it's sometimes better to switch the system off; although the wheels might spin, you might still be able to make forward progress. Just don't forget to turn the system back on.
If you have to drive on snowy or icy roads for an extended time, winter tires can make a dramatic difference. Their rubber is formulated to stay pliable at subfreezing temperatures, and their tread has more biting edges for better snow traction and ice braking.
Winter tires generally don't grip as well as regular all-season tires on pavement, which compromises braking and cornering grip, and they wear out faster. That's why you should go back to your regular tires when spring arrives. Be sure to mount winter tires on all four wheels to maintain balanced handling and take advantage of the improved braking on snow and ice.
Buying a separate set of wheels for winter tires makes it easier to switch back and forth but adds to the cost.
For very light snow, two-wheel drive will probably work fine. Front-wheel drive is preferred for slippery conditions, but either way you should get a vehicle with traction and electronic stability control. AWD or 4WD will provide added forward grip. And you'll get the most traction by combining any of those systems with winter tires.