Chevrolet 2003 Tahoe Owner's Manual page 14

Head Restraints
I
Adjust your head restraint so that the top of the restraint
is closest to the top of your head. This position
reduces the chance of a neck injury in a crash.
To raise the head restraint pull up on the head restraint.
On some models the head restraints tilt forward and
rearward also.
The rear seat head restraints in your vehicle may be
adjustable. They work the same as the front seat head
restraints, except they do not tilt forward and rearward.
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