I just lowered my xB on D2 coils and am now trying to buy new wheels. If I go 18x9 +30 all around will I need to buy any spacers? Also what would be a good size for tires? I was thinking of going 215/35/18 or 205/35/18. I'm also going to be rolling my fenders.

 

You'll need 12mm spacers on rear to get same flushness, or in your case poke (before rolling). And you'll need to swap in longer studs.
I'm running 225/40/18 on 18x8.5 with a very slight stretch but I'm not dropped that low; only TRD springs.