Buick 2003 Century Owner's Manual page 293

Storing the Flat Tire and Tools
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Storing a jack, a tire or other equipment in the
passenger compartment of the vehicle could
cause injury. In a sudden stop or collision,
loose equipment could strike someone. Store
all these in the proper place.
After you've put the compact spare tire on your vehicle,
you'll need to store the flat tire in your trunk. Use the
following procedure to secure the flat tire in the trunk.
When storing a full-size tire, use the extension with the
protector/guide, located in the foam holder, to help
avoid wheel surface damage. To store a full-size tire,
place the tire valve stem facing down, and then remove
the protector/guide and attach the retainer securely.
Store the cover as far forward as possible.
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