GMC 2011 Sierra Owner's Manual page 325

Any load that extends beyond
the vehicle's taillamp area must
be properly marked according to
local laws and regulations.
Remember not to exceed
the Gross Axle Weight
Rating (GAWR) of the front
or rear axle.
When you carry removable
items, you may need to put
a limit on how many people
you carry inside your vehicle.
Be sure to weigh your vehicle
before you buy and install the
new equipment.
Remember not to exceed
the Gross Axle Weight
Rating (GAWR) of the front
or rear axle.
Ladder Rack 340 kg
and Cargo (750 lbs)
Cross Toolbox 181 kg
and Cargo (400 lbs)
Side Boxes 113 kg per
and Cargo side (250 lbs
per side)
* The combined weight for all
rail mounted equipment should
not exceed 454 kg (1,000 lbs).
A. Primary Load Points
B. Secondary Load Areas
C. Cargo Management Option
Holes
Structural members (A) and (B) are
included in the pick-up box design.
Additional accessories should use
these load points. Depending on
the accessory design, use a
spacer under the accessory at
the load points to remove gap.