When assessing payload distribution, which components are considered?

When assessing payload distribution in dry van trailers, it is crucial to consider the structural integrity and support provided by various components. The side and end panels are significant in this regard because they play a critical role in maintaining the strength and stability of the trailer. These panels help distribute load evenly and are designed to withstand the pressures of the cargo while ensuring that the weight does not cause deformation or structural failure.

The other options, while they mention various structural elements, do not encompass the breadth of what is essential for evaluating payload distribution. For example, focusing only on top rails or limiting consideration to roof and floor components inadequately addresses how the entire structure interacts with and supports the payload. Thus, understanding the role of side and end panels provides a more comprehensive view of how the load is managed within the trailer, ensuring that safety and performance standards are met.