If you live in an area that experiences regular snowfall, you’re used to slippery roads, and you’ve likely purchased a 4-wheel drive (4WD) vehicle to get around safely.
If you’re not experienced with manually operated 4WD systems, however, it can be confusing to know when it’s appropriate to send power to all four wheels. Unless your vehicle has intelligent all-wheel drive (AWD) with computers controlling which wheel gets power, however, you probably have to manually push a button, twist a knob, or pull a lever to transfer from 2-wheel drive (2WD) to 4WD.
With that said, let’s take a closer look at when to engage your various driving modes:
Normal Driving: 2WD
When the road is dry, even, and paved, you can stick to 2WD. Even through rain and light snow, you probably won’t need to shift to 4WD so long as your tires are in good shape and you’re not driving too fast.
High Speed, Slick Roads: 4WD High
If you’re going to be driving through heavy rain or snow for more than a few minutes, shift into 4WD High, which maintains your standard gear ratios but sends power to all four wheels.
Off-Road, Up Steep Grades: 4WD Low
Low range multiplies torque, which means you can really put the power down to pull you through rough terrain. As the name implies, 4WD Low is for slow, steady crawling through deep sand, mud, or snow, as well as up steep inclines.
Why Not Use 4WD All the Time?
The reason you’ll only want to use 4WD in slick conditions is that when you turn your steering wheel, the tires can ever-so-slightly slip, which puts less stress on the clutches that engage 4WD. If you use 4WD on dry pavement, your tires will have more grip, and you’ll be increasing the forces on the 4WD system as the wheels move at different speeds from one another.
What About Locking Differentials?
If you’re in a serious off-road machine, you might have the option to lock some or all of the differentials, which means, instead of turning the wheels at different rates around turns or allowing some wheels to spin while others don’t, the 4WD system forces all wheels to spin at the same speeds.
As for why you’d want to do this, if you were rock-crawling, for example, there would be times when you may have a wheel or two in the air. Normally, these wheels would spin freely when stepping on the gas, but by locking the differentials, the vehicle can send power to the tires on the ground.
No matter what type of 4WD or AWD system you have, it’s only as good as the tires it powers. Most of the time, grippy tires will give you the traction you need without the need to engage 4WD. Snow tires, mud tires, and rain tires all do an excellent job of maintaining traction, depending on their respective conditions.
Of course, 4WD isn’t magic, but it can get you out of tough situations and hazardous conditions. Using it judiciously, driving smart, and keeping your vehicle in solid mechanical shape through regular maintenance and repairs will make the biggest difference.