sorry for all the questions, but what is a space leveler? when i got my 2.5 lift w/ 35 inch tires, the front tires were rubbing against the bottom front fenders, so i just cut out the corners to make more space. the back tires are very close to the side metal linings (i dont know what its called) on the both sides. is that gonna be a problem when i go off roading? how do i fix it?

 

I assume you're referring to the "pinch seam" in the front lower part of the rear fender opening. Most people that had interferance just trimmed it off with a Sawzall or something, or just bent it over. Cutting would probably work and look best, in my opinion. Just touch up w/ spray paint afterwards, to prevent any rust.

This assumes that your lift doesn't come w/ longer or adjustable rear arms. If it did, you can adjust them to put the rear axle back in the center of the wheel well, which should give you plenty of room.

 

your tires are rubbing when you flex it? do you have new wheels with less backspacing? you really didn't give us a lot of information here.
but, to answer your first question: Some JK's came with a forward rake (the vehicle was not level front-to-back), so people used 3/4" levelling spacers in the front to adjust for this. this will also compensate for a heavier bumper, winch, armor, whatever to some extent.