Ride Height is the height of your car or truck when it is sitting and the suspension is at the optimum setting (location). We can not stress how important setting ride height is on a chassis.
First, you need to pick out the wheels and tires you will be using in the front and in the rear. The diameter of the tire determines the ground clearance, frame angle, engine angle, shock length and correct angle to weld the front suspension.
After establishing the diameter of the tires, find the front spindle location based on the manufacturer’s specifications. The car manufacturers all have specifications on this. If you plan to install a front end kit, the manufacturer should also be able to provide you with this important information.
Take the radius of the tire diameter and use these measurements to set the distance from the ground. In the front measure from the center of the spindle and in the rear measure from the center of the axle. You now have “ride height” and everything should be relative to the ground. Of course the ground or suspension jig should be perfectly level as all your measurements will be made from this origin.