PURPOSE: To prevent the weight unbalance in the actual use on a vehicle by adjusting the balance of a tire assembly, keeping the tire pressure at a normal regulated traveling pressure.

CONSTITUTION: Air is poured into a tire T of a tire assembly TH in which the tire T is assembled onto a wheel H so that the tire pressure becomes a normal regulated traveling pressure, and balance is adjusted by installing a tire balance weight BW in order to correct the unbalance of the weight distribution in the tire assembly. Then, air is poured into the tire T further so that the tire pressure becomes the value higher than the normal regulated traveling pressure, and the tire pressure is always kept at the value higher than the normal regulated traveling pressure.