GMC Yukon XL Denali 2005 Owner's Manual page 390

3. Position the jack under the vehicle.
CAUTION:
{
Getting under a vehicle when it is jacked up is
dangerous. If the vehicle slips off the jack you
could be badly injured or killed. Never get under
a vehicle when it is supported only by a jack.
CAUTION:
{
Raising your vehicle with the jack improperly
positioned can damage the vehicle and even
make the vehicle fall. To help avoid personal
injury and vehicle damage, be sure to fit the
jack lift head into the proper location before
raising the vehicle.
5-82
Front Position
Front Tire Flat: If the flat tire is on a front tire of the
vehicle, you'll need to use the jack handle (C) and only
one jack handle extension (D). Attach the wheel
wrench to the jack handle extension. Attach the jack
handle to the jack. Position the jack on the frame behind
the flat tire where the frame sections overlap.
Turn the wheel wrench clockwise to raise the vehicle.
Raise the vehicle far enough off the ground so there is
enough room for the spare tire to clear the ground.