A spare tire is an extra tire carried in a vehicle to replace a flat or damaged tire. It is typically smaller and lighter than regular tires, designed for temporary use until the original tire can be repaired or replaced. Spare tires are often stored in the trunk or under the vehicle, depending on the design. There are two main types of spare tires: the full-size spare, which matches the other tires, and the compact or "donut" spare, which is smaller and meant for short distances. Having a spare tire is essential for road safety, as it allows drivers to address tire issues quickly and continue their journey.