Manufacturer Recommendations

• Trailers should have recommended tire pressures printed both in the owners' manuals and somewhere on an information placard, usually on the frame of the tongue.
  
  

Side Walls of Tires

• All tires sold in the United States are required to have factory-recommended tire pressures indicated on the side. Most tires indicated for truck and trailer use have a recommendation for both loaded and unloaded applications. If indicated, the recommended pressure for a loaded trailer should be followed.
  
  

Adjusting Tire Pressure

• Check tire pressure when the vehicle has been stopped long enough to allow tires to cool to the surrounding air temperature. This is a matter of safety and should be heeded fully: Any attempts to inflate to recommended pressures after just a couple miles of driving will result in operators insufficiently filling the tires and could result in tire failure -- particularly with highway driving.
  
  

General Recommendations

• Generally speaking, 16-foot car haulers have 14-inch to 16-inch tires, the standard dimensions for trailers that size. Inflation pressures for these tires range from 35 pounds per square inch to 75 pounds per square inch, depending on the tire's load capacity and manufacturing specifications.