Thought this thread was better to re ignite for help please if anyone can than starting a fresh one.

I have my other spare set of AU aftermarket rims that my mechanic mate is keen on putting them on his XH/G XR8 ute.
I can't find the specific info but I'm led to believe the rears will fit ? but the fronts will need a spacer - < if so does anyone know what thickness spacer is required ?
Thanks in advance.