These indicators are located on the tire's shoulders, parallel to each other. They also wear out with the tread like the Replacement Tire Monitor does. They visually represent the tread wear rate and manner of the tires and the vehicle's alignment. If the two parallel VAIs are identical in their wear, the vehicle's alignment is correct. However, if there is a difference between them, is means that the vehicle's alignment is off and it should be corrected before the tire develops an uneven wear pattern.