psycho91 said:
OK so I keep wondering this, will springs from a 4x4 trailblazer/envoy give a 2wd any lift or level the front out atleast, also what is the biggest tire that will fit in the back as IV noticed the back sits higher than the front
GM used over a dozen different stiffness springs in the factory, tuned to give the same sort of ride no matter what options were in the vehicle. So, yes - in general, 4WD springs are going to ride higher if installed in a 2WD vehicle. Or you can buy stiffer ones, except for the 2nd and 3rd most stiff springs in the catalog, which are now out of stock everywhere and GM isn't making any more.
Or you can keep your current springs, and add a 1 or 1.5" lift spacer inside the strut, depending on exactly how much lift your tape measure says you need to be level. SuspensionMAXX makes three different spacer thicknesses to allow that sort of fine tuning.
Larger tires in the back only are going to make it ride even HIGHER, and if you don't put the same size up front, then you can't rotate them properly. What's your purpose again?
In general, if you're not going to get into spacers to move the wheels outward, you need to limit the outer diameter to 30.5". Stock is 29". There are many tire size calculators on-line to help you find out what the outer diameter is for any proposed tire you want to buy.