Spare Tire - Usage in The 21st Century

Usage in The 21st Century

Contemporary vehicles may come equipped with full-size spares, limited use minispares, or have run-flat capability.

• The spare tire may be identical type and size to those on the vehicle. The spare may either be mounted on a plain steel rim or a matching road wheel as found on the vehicle. Among passenger vehicles, full-sized spares are usually provided for sport utility vehicles and light trucks, since a "limited use" spare would adversely affect such vehicles with higher centers of gravity. Due to the size of the full-sized spare, it is often mounted on the outside, such as the rear door of SUVs, and occasionally on the front hood.
• Certain vehicles are provided with a "limited use" spare tire, also known as a "space-saver," "donut" or "compact" spare tire — in an attempt to reduce cost, lower the vehicle's weight, and/or to save on the space that would be needed for a full-size spare tire. These supposed benefits are highly debatable; a space-saver is typically only 7kg lighter than a full-sized wheel. There is also the difficulty of transporting the full-sized wheel and tire once the space-saver has been fitted. The spare is usually mounted on a plain steel rim. They are typically smaller than the normal tires on the vehicle and can only be used for limited distances because of their short life expectancy and low speed rating. As well, due to the different size of a donut compared to regular wheel, electronic stability control and traction control systems will not operate properly and should be disabled until the original wheel is restored. Space saver spare tires also severely compromise the braking (especially on cars not fitted with anti-lock brakes) and handling of the car.
• In some cases, automobiles may be equipped with run-flat tires and thus not require a separate spare tire. Other vehicles may carry a can of tire repair foam, to repair punctured tires, although these often do not work in the case of larger punctures, and are useless in the event of a blow-out.