The value of tire pressure affects a number of important vehicle features. The article pays attention to assessing the impact of change in the tire pressure on change in both the rolling resistance and fuel consumption. The measurements were performed with four different values of tire pressure. The impact of change in the tire pressure on change in the rolling resistance has been measured during the driving tests. In order to measure the rolling resistance during tests, the measurement methodology has been made and device for measuring the rolling resistance has been constructed. The measurement of the impact of change in the tire pressure on change in the fuel consumption was performed via vehicle dynamometer. The result has shown linear dependence between the tire pressure and rolling resistance. These results measured points to the importance of keeping the correct value of tire pressure in relation to fuel consumption.