Can someone please tell me how to install spring spacers on my rear springs. Do I need to take off the springs and they sell them 4 to a pack. Do I just use one on each side or can I use two on each side ? I have 20" rims and the tire rubs.

 

Are you talking about Spring Blockers? Those are only used for when vehicles are being shipped to avoid them bouncing around.

It's not good to run them on the street, though some use them at the track (I do as well), but I never drive them on the street, because it makes your system way to stiff, and dangerous too on the highway.

I'd suggest you get a rear strut and spring combo that raises your rear end so your wheels don't rub.

How wide are your tires/rims?