I really have no idea what it is...they are Rally rims that came with the car. What is the easy way to find out?
You have to take the rim off the car and measure... see below on how to measure for backspacing...
Lay the rim down on the floor (outside of the rim (the shiney side we like to look at) faced towards the floor)and put a ruler (or something flat-straight) across the edges of the rim, so that it is right over top of the wheel mounting surface. Now measure from the wheel mounting surface to the ruler, or whatever you layed across the rim. This distance is the backspacing.
I need to double check my backspacing but I think it's around 4" and my 245/60/15's rub when I hit a slight bump. I also have the Hotchkis 2" lowering springs. The wheels and tires came with my car so I guess I'll have a couple of spares for the rear. My tires (BFG TA's) are 26.6" in diameter and 225/60/15's are 25.6". The 235's are 26.1".