ok advice needed currently have a 97 mk3 vr6 whhels are 205/40/17 trouble is they just seem sunk into the arch had 6 spoke audi tt wheels before they filled arch more , so looking to get some spacers hubcentric of course but how big can i go current wheel as said is 205/40/17 et 42 it says inside wheel, is a 15mm spacer to much comes hubcentric with longer bolts just want to bring wheel out more rear is the worst front not to bad to be honest

any advice would be grateful