What is the total gross weight limit for doubles/triples combinations?

Answer: C — 68,000 pounds

The total gross weight limit for doubles/triples combinations is 68,000 pounds. This limit is established by federal law for the maximum weight allowed on the interstate highway system. This is important for maintaining safety and preventing road damage, as heavier loads can lead to increased wear and tear on road surfaces and create hazards for other drivers. This weight limit applies to combinations of vehicles with two or more trailers. It's crucial for drivers to know and adhere to these regulations to ensure compliance with both safety standards and legal requirements. Understanding the gross weight limits helps drivers plan their loads appropriately and avoid penalties or accidents related to overloaded vehicles.