* Under the vehicle: This is the most likely location. You'll need to look underneath the rear of the vehicle. The spare is usually held in place with a retaining strap or other mechanism.
* Inside the vehicle: Less common, but possible, especially on models without a full-size spare. If this is the case, check the rear cargo area, possibly beneath the cargo floor. A smaller "temporary" spare might be located here.
To be sure, check your owner's manual. This is the definitive source of information for your specific vehicle. If you don't have the manual, you can often find a digital copy online through the Chevrolet website or a site like Haynes Manuals.