These are located on both of the shoulders parallel to one another and they wear along with the tread. If their wear is identical, it means that the alignment is correct and the tire's tread wear is even. If the wear is not identical, the vehicle's alignment is out of balance and the tread is wearing in an uneven manner. In these cases, the vehicle's alignment needs to be fixed before the tires adopt an irregular wear pattern. The irregular wear shortens the tread life and the tire's usability. Due to this, it is important to remedy the issue as soon as it is noticed, to prevent premature tread wear.