Scare go out of topic, not because you are TS...
Okay, we take that as a fitting to the Wira also...hahahaha
Offset from +35 should start to make your wheel come out. Of course if you want to come further out then use +30 or smaller number offset, if you can find.
Advantage is it will be more stable, better center of gravity, for looks depends on individual.
However with the tyres popping out from the wheel arch, you are likely to scrub your tyres on the fender. With the wheels further out, there is stress on your wheel bearings too.
Likewise if you use spacers you will have the same problem. But spacers have more cons. If the spacers are without the center cone positioning tyre vibrations will set in. If spacers are too thick, you need to mod the lugs to longer ones. There are also adapter type spacers but again stress on the bearings...
Haha, usually scared out of topic because it might confuse the TS. But since this is asked by TS, should be okay?
Okay, now I start to understand a bit about the pros and cons of offset. But the numerical part I am still not certain yet.
Spacers are something like this?
http://www.zerotohundred.com/newforums/chassis-and-wheels/439621-js-racing-original-wheel-spacers-fd2r.html
Located at the inside of the wheel?