Vehicles transporting more than ____ lbs total combined weight (including cylinders) must be ____ as required by DOT regulations or state law.

The correct answer is based on the regulations surrounding the transportation of LP-gas in vehicles. Specifically, vehicles that are transporting more than 1,000 pounds of total combined weight, which includes the weight of the cylinders, must be placarded. This requirement is enforced by the Department of Transportation (DOT) regulations as well as state law to ensure safety and proper identification of hazardous materials being transported.

Placarding serves a crucial safety function by notifying emergency responders and other road users that the vehicle is carrying a hazardous material. This is particularly important for LP-gas, which is flammable and poses a significant risk if there is a leak or accident. Therefore, proper placarding provides vital information regarding the nature of the cargo, enabling appropriate actions to be taken in case of emergencies.

Moreover, the weight threshold of 1,000 pounds is significant because it aligns with federal and state safety regulations, ensuring that adequate precautions and safety measures are observed during transport. Understanding these regulations is essential for anyone involved in the dispensing and transportation of LP-gas, as compliance helps to maintain safety for both the transporters and the communities they travel through.