Straight answers about trucks and the rules that run them.

Latest explainers

• How it works
  Why Are There Runaway Truck Ramps and How Do They Work?

  Runaway truck ramps use deep loose gravel to slow a truck with faded brakes. Learn how they work, what to do if you use one, and how to avoid needing it.

• How it works
  Sliding Tandems: Which Way to Pull and Why It Works

  Tandems over? Pull the tractor forward with trailer brakes set. Here's why that moves weight to your drives, and how to slide safely and legally.

• How it works
  Why Semi Trucks Use Air Brakes Instead of Hydraulic Brakes

  Semis use air brakes because the truck makes its own air, small leaks can be out-pumped, trailers hook up easily, and spring brakes act as a backup.

• How it works
  How a Fifth Wheel Locks a Trailer and How to Check It

  The kingpin drops into the fifth wheel jaws and a spring lock wedges behind them. Here's how it works and the checks that prove the trailer is coupled.

• Myth vs fact
  Should You Idle a Diesel to Warm It Up in Cold Weather?

  Idling a diesel for half an hour is mostly a myth. Learn what really warms a cold engine: block heater, short idle, gentle driving, winter fuel.

• Classic rigs
  Kenworth W900: Why This Long-Hood Truck Became a Legend

  The Kenworth W900 debuted in 1961 and kept its long hood and boxy grille for 60+ years. Here's why drivers still want one, and what it costs in wind.

• How it works
  Do Trailer Side Skirts Really Save Fuel? What They Save

  Side skirts cut drag under a trailer and typically save a few percent of fuel at highway speed. Here is the math, the catch, and who benefits.

• Rules
  11-Hour vs 14-Hour Rule: How the Driving Clocks Work

  The 11-hour rule counts driving only. The 14-hour rule is a window that never pauses. Here is how both work, plus the 30-minute break.

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