GMC 2012 Sierra Series Owner's Manual page 484

10-84 Vehicle Care
Front Position - 1500 Models
4. Position the jack under the
vehicle, as shown. If the flat tire
is on the front of the vehicle
(1500 Model vehicles), position
the jack under the bracket
attached to the vehicle's frame,
behind the flat tire.
Front Position - All Other Models
Position the jack under the
vehicle, as shown. If the flat tire
is on the front of the vehicle (all
other models), position the jack
on the frame behind the flat tire.
I n f o r ma t i o n P r o v i d e d b y :
Rear Position 1500 Models
5. If the flat tire is on the rear, for
1500 models position the jack
under the rear axle about 5 cm
(2 in) inboard of the shock
absorber bracket.