What is a sign that a vehicle may have under-inflated tires?

A sign that a vehicle may have under-inflated tires is vibration at high speeds. Under-inflation can lead to an imbalance in the tire, which affects its performance and can result in a noticeable vibration when driving at higher speeds. This occurs because the tire does not maintain its intended shape and contact with the road, causing uneven wear and instability.

Other options do not indicate under-inflated tires effectively. A smooth steering feel often suggests adequate tire pressure, while worn tread in the center could imply over-inflation rather than under-inflation, and increased fuel efficiency typically occurs with properly inflated tires. Understanding these symptoms helps drivers maintain vehicle safety and performance.