Hummer 2006 H3 Owner's Manual page 222

Roll Your Tires Over Large Rocks
4-26
Do not straddle large
rocks; drive over them,
letting the tire envelop 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, your vehicle will cross logs
up to 10 inches (25.4 cm) in diameter. Approach the
log at approximately a 15 degree angle (A) with
the transmission in FIRST (1) and the transfer case in
Four-Wheel-Low Lock and "walk" your vehicle over, one
tire at a time. As with all obstacles, face your tires
perpendicular to the object for best traction and tire life.
It may be necessary to modulate your brake pedal
and accelerator to avoid spin-out. Ease the vehicle down
from the log with your brake.