Why Can't a Spare Tire Be Used as a Regular Tire?

[DeClaire]

Spare tires cannot be used as regular tires for the following reasons: spare tires have different friction coefficients, ground adhesion, and air pressure compared to other tires. Prolonged use can affect the vehicle's braking system, steering system, and suspension system, posing significant safety hazards. Additionally, since spare tires and original tires are manufactured at different times, their aging, hardening, lifespan, and deformation vary. Therefore, long-term use is unsafe. Spare tires should be replaced with original tires as soon as possible after emergency use. Moreover, regardless of their width, spare tires have specific production and usage requirements set by manufacturers. Since spare tires are not used regularly, they do not experience wear. Using a brand-new tire alongside heavily worn tires can create safety risks. Currently, there are three internationally recognized types of spare tires: the first type is identical to the regular tire, known as a full-size spare; the second is a non-full-size spare, commonly referred to as a narrow tire, usually smaller in size; the third is a folding spare tire, which is stored folded in the trunk and inflated when needed for emergency use. The difference in size between spare tires and regular tires is primarily for safety reasons. Since car tires inevitably wear over time, even if a spare tire is of normal size, the difference in wear between the spare and the other tires can create safety hazards. To discourage long-term use of spare tires, manufacturers intentionally make spare tires smaller to prompt drivers to replace them with regular tires promptly. Spare tires also require maintenance: Regular inspections are necessary because spare tires are rarely used and often overlooked. When needed, drivers may find the spare tire flat or cracked, leading to significant issues. Avoid oil contamination. Oil products should not be stored with spare tires, as rubber, the main component of tires, is highly susceptible to damage from oil exposure. Some externally mounted spare tires are exposed to harsh weather conditions, which may shorten their lifespan.