Proper alignment of the front wheel is a time-consuming and tedious procedure, which involves complex and costly devices and it is best to leave their tasks to a specialist with the actual equipment. It can be useful to know the fundamentals of front end alignment to be able to deal wisely with the shops that offer this. Toe-in The front wheels will be perpendicular to each other when the steering is straight ahead; in a car with zero toe-in, the distance between the front and rear edges of the wheels is the same. In the Mazda RX-7, the toe-in is static with 0.24 in (6 mm), the front edges are supposed to be lower than the rear edges by 0.48 in (12 mm) and this results in improper tire wear should incorrectly set. Toe-in is changed by changing the length of the suspension tie rods. The angles at which the tire and the suspension upright is inclined to the vertical are called camber and caster whose angles influence tire tread contact and steering-wheel self-centering respectively. Camber and caster adjustments include loosening the four attaching nuts that have to be located on the top of the suspension strut and moving the strut mounting block to the right or left to get the appropriate angles, in the case of the RX-7, the angles are 1 10 plus or minus 30 for camber and 400 plus or minus 45 for caster.