What is a key indicator of axle misalignment in a trailer?

Uneven tire wear serves as a key indicator of axle misalignment in a trailer because it reflects how the tires interact with the road surface. When the axles are not aligned properly, the tires may wear down on one side more than the other due to improper contact or differing angles of rotation. For instance, if one axle is slightly bent or misaligned, the corresponding tires on that axle will experience different forces, leading to a discrepancy in wear patterns. This issue can be observed as bald spots or unusual wear on the edges of the tires.

While increased fuel consumption, difficulty in steering, and leaking brake fluid can indicate other mechanical problems, they do not directly point to axle misalignment in the same clear manner. Increased fuel consumption might be a result of various factors, including tire pressure or engine issues, while difficulty in steering often suggests problems with the steering mechanism rather than the axles themselves. Similarly, leaking brake fluid typically indicates brake system issues, which are separate from axle alignment concerns. Thus, uneven tire wear is a specific and reliable symptom that indicates misalignment, making it the best indicator among the options provided.