2010 Hummer H3 Owner's Manual - Page 198

9-14 Driving and Operating Roll The Tires Over Large Rocks the vehicle over, one tire at a time. It may be necessary to modulate the brake pedal and accelerator to avoid spin-out. Ease the vehicle down from the log with the brake. Crossing Obstacles Approach Angle - a Key to Mobility If you encounter a large dip in the terrain, do not enter straight on; enter at an angle - 15° minimum approach (A), 75° maximum approach angle (B). For very large dips, ditches or small washes, coast in, using the engine as a brake (transmission and transfer case lowest gears). Then, use the low ranges in the transmission and transfer case to power out. Do not straddle large rocks; drive over them, letting the tire cover the rock. The tread of the tire is thicker and tougher than the sidewall of the tire and is more resilient to impact than underbody components. Log Crossing Using the proper technique, the vehicle will cross logs up to 25.4 cm (10 inches) in diameter. Approach the log at approximately a 15° angle (A) with the transmission in 1 (First) and the transfer case in Four‐Wheel‐Low Lock and "walk" Driving on Hills Off-road driving often takes you up, down, or across a hill. Driving safely on hills requires good judgment and an understanding of what the vehicle can and cannot do. There are some hills that simply cannot be driven, no matter how well built the vehicle.