sidewaysbo

hi i dont know if this come s under technical but i really need some help i am trimming out steel arches and plastic arches front and rear , i ordered a set of wheels today i think the guy i was talking to doesnt realise how far i want to push the wheels out to the max i have ordered team dinamics the no real dish wheel on the rim 8x17 et25 rear is 9x17 35 does anyone know how far i can go on lowering the ets of front & rear wheels of this width i got to phone back first thing in the morn so help on this would reall y help thanks bo