In the book SN-Ratio for the Quality Evaluation published by the Japanese Standards Association (1988), a study on how tire air pressure affects the maneuverability of an automobile was conducted. Three different tire air pressures were compared on three different driving surfaces. The three air pressures were both left- and right-side tires inflated to 6 k g f/ cm2, left-side tires inflated to 6 kg f/cm2 and right-side tires inflated to 3 kg f/cm2, and both left- and right-side tires inflated to 3 kg f/cm2. The three driving surfaces were: asphalt, dry asphalt, and dry cement. The turning radius of a test vehicle was observed twice for each level of tire pressure on each of the three different driving surfaces. Comment on the interpretation of the main and interactioneffects.

Tire Air Pressure 11 Asphalt 44.0 25.5 34.2 37.2 27.4 42.8 Dry Asphalt 31.9 33.7 31.8 27.6 43.7 38.2 35.5 34.6 27.3 39.5 Dry Cement 46.6 28.1