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Updated October 17th, 2016

Most of us are familiar with the benefits of 4-wheel drive. Your vehicle will have much better traction on rough terrain such as dirt roads, hard-packed sand, snow, or even rocky surfaces when in 4-wheel drive. Four-wheel drive (4WD) can also come in handy when you're going up a steep incline or decline; it can give you more power to help you climb those steep grades, along with better control and braking capability on your descent. Four-wheel drive is normally activated by a lever near the gear shift or a switch on the vehicle's console; once engaged, it will transfer drive either partially or entirely to the rear differential. You've probably seen the labels "2H", "4H" and "4L" on the 4WD lever or switch, but what exactly do they mean, and when should you use each one? Read on to find out the answer.

2H is typically used for regular or everyday road driving. On this setting, the vehicle is driven in the high range by the two rear wheels. If the vehicle has all-wheel drive or constant 4-wheel drive, it will not feature the 2H option.

4H is also used under relatively normal road conditions, but it specifically comes in handy when you need a little extra traction. You might be on a dirt road, some hard-packed sand or an icy or snow-covered road; in any one of these scenarios, you're going to need your vehicle to be able to hug the road a little better so that you won't be slipping and sliding all over the driving surface. In the 4H setting, both the front and rear wheels are involved in providing traction and stability by way of being engaged in high-range.

4L is for the heavy-duty driving tasks such deep ruts, deep snow or mud, large rocks, loose sand, and extremely sharp inclines or declines. While the wheels have a slower rate of revolution in this mode, they offer a higher degree of torque, which helps them cling to slippery or volatile surfaces. Yes, you will have a reduced speed in 4L, but your vehicle will be much more sure-footed on the driving surface.

Tire pressure is another important factor that should not be overlooked. You should always try to adjust your tire pressure to best match the terrain. If you're on a driving surface with particularly poor traction, you can lower the tire pressure slightly to create a larger footprint for the tire on the road. With more rubber making contact with the driving surface, you have less of a chance of undue slipping and sliding all over the road. For most large 4WD tires, 38 psi is a normal level of air pressure, but when you're dealing with exceptionally rough driving terrain, consider dropping the pressure to about 30 psi in order to create more of a "cushion effect" for the tire on the road. For this reason, it is always a good idea to keep a tire gauge and air compressor in your vehicle so that you can make these adjustments on the fly when necessary.

Whether you're on an off-road adventure or you happen to be caught in some unexpected rough terrain, keep this information in mind to help you know when and how to use your 4WD. If you do, it will save you a lot of time and headaches, as well as money spent in unnecessary repairs.

*Always check your owner’s manual for your vehicle model’s specific instructions before attempting any type of repair.

Hogan & Sons Tire and Auto provides automotive safety and auto repair information for the sole purpose of educating the community at large. “We believe an educated customer is a loyal customer.” Hogan and Sons Tire and Auto in Winchester, Virginia. 8 locations throughout the Northern Virginia to choose from. http://www.hoganandsonsinc.com  

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