The automatic tire inflation status measurement system comprises a scale and a tire-deformation apparatus for automatically determining whether a pneumatic tire installed on a vehicle is underinflated. The scale plate is flush mounted with the road surface and measures the weight on the tire as the tire rolls across the plate. A second weight measurement is made by using a deformation bar which projects slightly above the road surface and causes the tire to deform as it rolls over the bar. Both the scale and deformation bar are connected to load cells, preferably the same load cells. The tire deforms as it rolls across the bar and weight on the bar vs time is measured by the load cells. Data from the load cells is collected by, for example, using a summing amplifier and a computer-operated data acquisition board. The peak reading on the scale and the peak value of the bar reading are used to calculate a ratio. This ratio is then compared to a threshold value to determine whether the tire is underinflated. The result of this analysis is communicated to the vehicle driver, for example, by an electronically controlled display, such as a visual message display, computer speech generator or printer output, connected to the computer.