GMC Yukon Denalid Owner's Manual page 408

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 5,000 lbs (2 270 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.
408
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. Always
leave just enough slack so you can turn with your
rig. Never allow safety chains to drag on the
ground.
Trailer Brakes
If your trailer weighs more than 2,000 lbs (900 kg)
loaded, then it needs its own brakes – and they
must be adequate. Be sure to read and follow the
instructions for the trailer brakes so you'll be
able to install, adjust and maintain them properly.
Since your vehicle is equipped with the
®
StabiliTrak system, your trailer brake system
cannot tap into the vehicle's hydraulic brake
system.