How long should a tractor trailer idle?

A tractor trailer should ideally idle for no more than 5 to 10 minutes, as prolonged idling can waste fuel and increase engine wear. Many modern engines are designed to warm up quickly, and excessive idling can also contribute to unnecessary emissions. It's best to turn off the engine when parked for extended periods and only restart when necessary. Additionally, some jurisdictions have regulations limiting idling time to reduce environmental impact.