skelsong

would you guys tell me what is mean staggered and non staggered. when i check the wheels websit, some of the wheel have staggered and non staggered.also, for the 240sx, i check a lot of people put 38offset rear 18X9.8 245/45/18, 18X8.5 fornt 35offset 225/45/18.. is it really fit the 240sx?, or should be more less offset.because i was worry that if too much inside it will crash the inside some thing, for example, suspenson or other things. if too much come out, it will be hit the rear or fornt frender. so, what is the best offest for 18" 225fornt and 245rear. thank you so much.please expalin more detail. thanks