Which of the following factors can shorten a tire's life?

Answer: B — Unbalanced wheels

Unbalanced wheels can significantly shorten a tire's life due to their impact on how the tire makes contact with the road. When wheels are unbalanced, it creates uneven weight distribution as the tire rotates. This can lead to vibrations that not only make for a less comfortable ride but also result in uneven tire wear. Over time, this uneven wear can compromise the integrity of the tire, leading to a higher likelihood of flats or blowouts, and ultimately necessitating earlier replacement. In contrast, properly aligned wheels and consistent tire pressure contribute to even tire wear and prolong the tire's lifespan. All-season tires are designed to provide versatility in various conditions, but their use does not inherently shorten tire life when they are properly maintained.