Which component is NOT critical for driving safety in commercial vehicles?

Engine sound levels are not considered a critical component for driving safety in commercial vehicles. While monitoring engine sounds can be indicative of various mechanical conditions or issues, they do not directly influence the immediate safety of operation compared to other factors. For instance, maintaining proper tire pressure is essential as it affects traction, stability, and braking performance. Similarly, understanding and calculating braking distances is crucial for maintaining safe following distances and ensuring that a vehicle can stop in time to avoid collisions. Vehicle stability is fundamental to preventing rollovers and maintaining control, especially while turning or during adverse weather conditions. Therefore, while monitoring engine sounds is beneficial for overall vehicle maintenance, it does not hold the same level of immediate impact on safety as the other components mentioned.