Hummer 2008 H2 Owner's Manual page 284

The HUMMER H2 has an approximate approach
angle (A) of 42° and a departure angle (B) of 37°.
4-16
Design specifications required a minimum gradeability of
60% (31°) slope, with the vehicle fully loaded, on high
friction surfaces at 6 mph (9.7 km/h). The vehicle is
expected to traverse this grade only for short durations.
Never stop and idle the vehicle or park it on this grade.