Off-roading is a popular motorsport here in Pennsylvania. For many, a trek over rocks, through mud, or across dunes is an exhilirating driving experience. To enjoy off-roading, you don’t have to have formal automotive training – but there is technical information every beginner should know.
Inside the Gearbox: Making the Right Choice
Most 4WD vehicles have a dual-range transfer case sending power to drive wheels. Everyday driving happens in 2H (two-wheel-drive, high range). Selecting 4H (four-wheel-drive, high range) sends power to all wheels at high-speed. For maximum traction, 4L (four-wheel-drive, low range) powers the wheels more slowly to improve torque, traction, and control.
Wheel Hubs: Getting It All Locked-In
Front hubs lock hub and wheel to the output shafts, allowing the front wheels to receive power. Manual hubs require the user lock them at the wheel. Automatic locking hubs engage whenever the operator selects 4H/4L but may require the vehicle be reversed to disengage.
Tires: Where Rubber Meets Road… or Mud… or Sand… or Rocks
Manufacturers offer off-road tires for conditions from mud and sand to rocky terrain. Matching tires to expected conditions is very important, as tread patterns and compositions vary greatly.
While normal tire pressure for most 4WD vehicles is approximately 38 PSI; terrain can affect this. The lower the pressure, the larger the contact patch. This improves traction and provides cushioning, though risk of puncture or separation increases.
On rough, dusty trails; 30 PSI may work. For mud or rocks, recommendations are 20-25 PSI. On hard sand, the number drops to 18 PSI – going to 12 PSI for soft dunes. On water or icy surfaces, a larger contact patch will increase the risk or hydroplaning; so recommendations are higher.
Taking Measurements: Angle, Approach, and Travel
On rough terrain, some vehicles are more capable than others. With that in mind, there are measurements and dimension you’ll need to know in order to avoid getting stuck:
- Approach Angle: The maximum incline to ascend before body or suspension touches
- Break-Over Angle: The maximum angle to drive over without bottoming-out
- Departure Angle: The maximum incline to descend before body or suspension touches
- Wheel Articulation: The maximum distance each wheel can move up or down
- Wheelbase: The center-to-center distance between the vehicle’s front and rear wheels
The Most-Important Rule: Be Prepared
Off-Road travel means going away from civilization. That means away from assistance as well. Off-road vehicles can get stuck or break down. Rollovers and accidents can cause injury. That’s why experienced off-roaders prepare – and never travel alone. Essential equipment includes:
- For Your Vehicle: Tow Rope, Spare Tire/Tools, Tire Gauge, Air Compressor, Winch
- For You: Navigational Aids, First Aid Kit, Mobile Phone, Two-Way Radios