245's hard to get a load rating for, alot of tyre places around me don't do them unless they're expensive tyres.
225/35's also protect more from potholes - then again you don't plan on hitting one like I did :S...
Being a VY, whatever choice you make if you're that fussy you can go Holden and get them to re-calibrate it for $90. I did it when i got my Diff gears done
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I honestly would prefer the 245/30's though, you can go lower on them as they aren't as high, my 225/35's scrub on the front wheel arches on super lows on (big) bumpy corners. Not alot, but it does happen now and again.
But once again depends on the offset as Sweefu has suggested.
Goodluck - Either one will do fine, 225/35's will be cheaper though.
Edit: Just a tip, When i got my 225/35/20's fitted on ultra lows (about 60mm lower than standard) if i didn't get my guards rolled at the same time i wouldn't of been able to drive without chewing out the tyre. I suggest getting the rears (or even fronts - but they mainly rolled themselves slowly) rolled before lowering.
