Is the Spare Tire of a Sedan the Same as the Original Tire?
4 Answers
Sedan spare tires are not the same as the original tires. Spare tires are only suitable for slow-speed and short-distance driving. Prolonged use can affect driving safety. Most car spare tires are not full-size tires and, unlike the original tires, are not perfectly matched to the vehicle for long-distance travel. Spare tires also have a limited lifespan. Even if they are frequently stored unused at the back, they are still made of rubber and generally have a service life of about five years. After this period, it is recommended to replace them, or a repaired tire can be used as a spare. It is important to note that spare tires are only for temporary use and should not be used long-term, as this can significantly impact safety.
A few days ago, I had a flat tire from a nail puncture and only then realized how different the spare tire was compared to the original when using it for the first time. Most sedan spare tires are non-full-size, narrower than the original tire, with steel rims made of iron. Manufacturers design them this way mainly to save trunk space and reduce weight, considering spare tires are rarely used for years. After installation, the dashboard immediately showed a tire pressure warning, with a maximum speed limit of 80 km/h, and the ride felt noticeably unstable. I hurried to a repair shop to fix the punctured tire, where the experienced mechanic said such spare tires are only for temporary emergencies—shallow tread patterns and no drainage grooves make them prone to slipping in rain. Regularly check the spare tire’s pressure every quarter, and even if unused, the rubber expires in about five years and needs replacement.
After ten years in auto repair, I've often seen car owners using spare tires as regular ones, which is actually very dangerous. There are two types of spare tires: non-full-size ones that look like small motorcycle tires, and full-size ones that are the same size as the original tires but made of much poorer material. Original tires have thick sidewalls with noise-canceling foam, while spare tires are made of hard rubber and produce a lot of noise when driven. When changing to a spare tire, pay special attention to the bolt torque—I've adjusted it four times myself with a torque wrench, as even a difference of 10 Nm can cause the wheel to shake. Last year, a car owner drove on a spare tire on the highway and lost grip while turning, crashing into a guardrail and incurring over 40,000 yuan in repairs. Nowadays, new cars don’t even come with spare tires; they just provide tire sealant, which is more convenient but only works for small punctures.
Don't think the spare tire can be used as a substitute! My uncle's Audi originally had run-flat tires, but the spare was just a regular tire. Last time after a flat and switching to the spare, the braking distance noticeably increased. The spare tire's rim is usually made of steel, weighing three kilograms more than the original aluminum alloy rim, increasing inertia during turns. The tire pressure also needs to be higher—most spare tires require 4.0 Bar. I always measure it twice with a digital gauge when changing tires. The new car manual states that spare tires are speed-limited to 80 km/h and have a lifespan of about 5,000 kilometers. Last month on the expressway, I saw a Volkswagen Bora with a flat tire—the driver drove too fast on the spare, causing the tread to delaminate completely.
