We often get the phone call or email saying "I don't know how much I want to lower my ride." The best way to get an idea is to measure.
Here is how to successfully do that:
1) Park your vehicle on a level surface. By doing this you ensure accurate results when getting the vehicle's ride height measurements
2) By using a measuring tape start from the center of the axle hub going straight up to the bottom of the fender lip.
3) Repeat this process for all four sides.
This is also a process we recommend BEFORE you install your lowered/lifted suspension. By having before and after measurements you can know the total actual amount of ride height you have achieved.
Now that you have figured out the ride height for your vehicle you want to know what size wheels and tires will work. We typically won't suggest a size to you unless we have personal experience with the same vehicle and suspension as you.
We do have a niffy tool from the guys over at Discount Tire to use. By using their Tire Dimensions tool you can see what tire size and rim will work. http://www.discounttire.com/dtcs/infoTireMath.dos
Ya we just gave you some homework, but hey look at it this way at least by doing the measurements we can ensure you order the right stuff the first time and will be happy with your new stance.