The bead wire has the function to form and bound the tire’s outline when inflated . Besides, through the bounding and strength of the rim, it becomes to operate loading effect. Under the vehicle was loaded and ran in high speed, it is very dangerous if there were not suitable dimension between bead wire and rim . So that, the high level tire production factories are paying close attention to the properties of the bead wire and rim.
Although the tire makers have the knowledge or the equipment to measure the bead wire’s length , the measured data might be different due to man-made mistake . Therefore, needing a high precise and steady measuring equipment is necessary.