To compare to stock suspension height -
Stock shackles are 4" bolt-to-bolt.
Measure your shackles (center of bolt-to-center of bolt), subtract 4, divide by 2. This is your shackle lift.
Stock tires from factory = ~27" diameter (205/75/15 or 215/75/15 depending on model)
Take your tire diameter, subtract 27, divide by 2. This is your tire lift.
To start: Measure from the ground up to the bottom of your rocker panel to get your rocker panel height.
- Subtract the stock rocker panel height (18") from your measured rocker panel height - this is your total lift over factory height (tires, springs, shackles)
- To get total suspension lift (just springs and shackles): subtract your tire lift from your total lift (#1)
- To get spring lift only: Subtract your shackle lift from your total suspension lift (#2)
Keep in mind that unless you have identifying marks on the springs that allow you to look up the part number, it will be difficult to accurately determine the advertised lift for the springs. Some springs hold their advertised lift height well, others not so much, depending on how they are used/abused. The best you can do in that case is measure the actual lift being provided.