Hummer 2008 H2 Owner's Manual page 285

Also, your vehicle should be able to traverse a 40%
(22°) side slope at 6 mph (9.7 km/h) while fully loaded
on high friction surfaces.
Your vehicle can climb a 16 inch (40.6 cm) vertical step.
Step climbing is best done by approaching the step at
an angle rather than straight on.
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