You center hole should also be at least 66.1mm diameter in order for the wheels to fit an I30.
Backspacing gets a little trickier. All rims should have a embossed/stamped backspacing on them somewhere. Look for ET40 or whatever two numbers comes after the ET is your backspacing. From what I have been able to find out so far on my own, +45, +40, +35 positive backspacing is OK on the I30, not sure of what other backspacings will work out OK. I have been looking at some rims with only a +25 backspacing, but have not put one on my car yet to see just exactly how much of the rim will be sticking out from under my fender, if any.
As the other guy stated already, your bolt pattern on the lugs will be a 5 x 114.3mm pattern so any rim you use has to have this bolt pattern to work.
