Which characteristic does NOT apply to air suspension?

Air suspension systems are designed to provide a flexible and adjustable ride quality, making them particularly well-suited for vehicles that need to accommodate varying loads. One key characteristic of air suspension is that it indeed does not provide much roll stiffness. Roll stiffness refers to a vehicle's resistance to leaning or tilting during cornering. Air suspension systems, while offering a smoother ride especially when unloaded, typically have a softer setup compared to traditional leaf or coil spring systems, which can result in less roll stiffness.

This lower roll stiffness is beneficial for comfort, but it may also lead to more body roll during turns, which can affect vehicle handling and stability. Therefore, the characteristic of not providing much roll stiffness accurately describes one of the fundamental performance traits of air suspension systems, making it the correct answer in this context.

In contrast, attributes related to the ride quality when a truck is empty or the longevity of components are more aligned with the benefits typically associated with air suspension systems.