Chevrolet 2007 TrailBlazer Owner's Manua page 375

Hitches
It's important to have the correct hitch equipment.
Crosswinds, large trucks going by and rough roads
are a few reasons why you'll need the right hitch.
Weight Distributing Hitches and Weight
Carrying Hitches
(A) Body to Ground Distance, (B) Front of Vehicle
When using a weight-distributing hitch, the hitch
must be adjusted so the distance remains the
same both before and after coupling the trailer to
the tow vehicle.
If you use a step-bumper hitch, the bumper could
be damaged in sharp turns. Make sure there is
ample room when turning to avoid contact between
the trailer and the bumper.
If you will be pulling a trailer that, when loaded,
will weigh more than 4,000 lbs (1 814 kg) be sure
to use a properly mounted weight-distributing
hitch and sway control of the proper size.
This equipment is very important for proper vehicle
loading and good handling when driving. Always
use a sway control if the trailer will weigh
more than these limits. You can ask a hitch dealer
about sway controls.
Safety Chains
You should always attach chains between your
vehicle and your trailer. Cross the safety
chains under the tongue of the trailer to help
prevent the tongue from contacting the road if it
becomes separated from the hitch. Instructions
about safety chains may be provided by the hitch
manufacturer or by the trailer manufacturer.
Follow the manufacturer's recommendation for
attaching safety chains and do not attach them to
the bumper. Always leave just enough slack so
you can turn with your rig. Never allow safety
chains to drag on the ground.
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