Why can't the total mileage of a spare tire exceed 100 kilometers?
2 Answers
It depends on whether it's a full-size spare tire or a compact spare tire. If it's a compact spare tire, it is designed for short-term emergency use only, with lower specifications and speed ratings, so the speed generally should not exceed 80 km/h. Full-size spare tire: A full-size spare tire has exactly the same specifications as the other four tires on the vehicle and can replace any temporarily or permanently unusable tire. Compact spare tire: This type of spare tire has a slightly smaller diameter and width compared to the other four tires, so it can only be used as a temporary replacement and must be installed on non-driving wheels. Additionally, the maximum speed should not exceed 80 km/h.
Once when I was on a long drive using the spare tire, the mechanic specifically warned me to replace it within 80 kilometers at most. The spare tire is thinner than regular tires, with a different rubber compound, primarily designed for emergencies. Standard tires have 7 reinforced cord plies on the sidewalls, while spares only have 2 layers—prolonged driving can cause the rubber to overheat and soften. The tire width is over 20% narrower, reducing grip during sharp turns and increasing the risk of skidding. Most critically, the tire pressure system isn't compatible; extended use can easily deform the wheel rim, and repairing a rim costs far more than replacing a spare. My neighbor once insisted on driving 150 kilometers with it, resulting in complete failure of both the wheel hub and bearings, costing nearly 5,000 yuan in repairs.
