Spare tire

A spare tire or spare tyre (or stepney) is an additional tire (or tyre - see spelling differences) carried in a motor vehicle as a replacement for one that goes flat, a blowout, or other emergency. Spare tire is generally a misnomer, as almost all vehicles actually carry an entire wheel with a tire mounted on it as a spare rather than just a tire, as fitting a tire to a wheel would require a motorist to carry additional, specialized equipment. However, some spare tires ("space-saver" and "donut" types) are not meant to be driven long distances. Space-savers have a maximum speed of around 50 mph (80 km/h).

When replacing a damaged tire, placing the compact spare on a non-drive axle will prevent damage to the drivetrain. If placed on a drivetrain axle, the smaller-diameter tire can put stress on the differential causing damage and reducing handling.

The early days of motor travel took place on primitive roads that were littered with stray horseshoe nails. Punctures (flat tires) were all too common, and required the motorist to remove the wheel from the car, demount the tire, patch the inner tube, re-mount the tire, inflate the tire, and re-mount the wheel.

To alleviate this time-consuming process, Walter and Tom Davies of Llanelli, Wales, invented the spare tire in 1904. At the time, motor cars were made without spare wheels. Their company, Stepney Iron Mongers, had agents distributing the United States, Belgium, France, and Italy. The word "stepney" is sometimes used interchangeably in countries that were once part of the British Empire such as Pakistan, Bangladesh, India, and Malta

The first to equip cars with an inflated spare wheel-and-tire assembly were the Ramblers made by Thomas B. Jeffery Company. The Rambler's interchangeable wheel with a mounted and inflated spare tire meant the motorist could exchange it quickly for the punctured tire that could then be repaired at a more convenient time and place.

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