Can a Car Spare Tire Float in Water?
2 Answers
Car spare tires can float in water. Here are the specific details about spare tires: 1. Material: Car spare tires are made of rubber. 2. Long-term storage: The performance of rubber products will degrade over time, and spare tires may naturally burst. Tires stored for a long time will accumulate dust, so it is necessary to regularly check the air pressure and surface smoothness of the spare tire. Regular cleaning will help preserve the spare tire. Long-term storage can lead to surface hardening of the spare tire. Once the spare tire reaches the end of its lifespan, the rubber will harden, lose its original flexibility, and become prone to damage or even cracking.
Spare tires generally don't float in water, which I've personally experienced. Most spare tires consist of steel rims covered with rubber, making them quite heavy overall with a density higher than water, so they sink immediately when thrown in. For example, the rubber of common tires has a density of about 1.1g/cm³, while the steel rim is as high as 7.8g/cm³, compared to water's 1g/cm³, so it sinks right away. I once tested this while repairing a car—I tossed a spare tire into a shallow pool, and it showed no signs of floating, unlike a lifebuoy. When driving through water, if the trunk gets flooded, the spare tire fixed there won't help at all; instead, getting soaked can lead to rust, affecting its usability for future tire changes. I recommend not experimenting out of curiosity—spare tires are designed for emergency tire changes, not water rescues. If your car encounters a flood, prioritize escape plans rather than relying on tires as flotation devices. Usually, keep the car interior dry to prevent the spare tire from being exposed to moisture, maintaining it in good condition for emergencies.
