Spacers for stock 18''s?

[simota1]

hey everyone i have spent like almost an hour going crazy looking for spacers threads and reading all of them... but it seems everyone has put them on the rays rims... i dont think they have ever put them on the 18''s

so i was wondering would 20mm be good enough for the rear or would i need a bigger wheel spacer like a 25mm i want my rim flush with the body not going in like it is i am going to go with the ichiba v2 spacers since i dont wanna replace the studs...

Also is 15mm spacer for the front good enough? im really sorry if this is a repost but seriously there is soooo much threads on this topic and i got tired of trying to look for someone that has done them on 18''s

One LAST thing... i plan takin my car to the track... as soon as i get some performance parts in.... do SPACERS propose a threat of any kind? can it cause an accident even if i travel speeds of 100+ MPH?

THANKS EVERYONE for there help