[cdmulders]

Custom spacers - cool! Regarding rubbing, 17mm spacers for the front wheels seem too high, but it certainly depends on the offset of the G30 wheels you are proposing.

I attempted a 15mm spacer on my front wheels with a 18" x 8" winter wheel with 41mm offset, and a 245mm wide tire (245 / 50 / 18), as an experiment. Why is a longer story. Anyway, the front wheels rubbed on the fender when I turned a corner, but my car is lowered and those tires were oversized at 50 profile vice 45, which means the tires were taller than stock). I ended up dumping those tires / wheels and getting a more normal 18" x 8.5" wheel with 32mm offset, and 245 / 45 / 18 tires.

If your G30 wheel (19" x 9") has an offset of around 40mm or less, then I'd be concerned for the front wheels. Whether your wheel is 9" or 8.5" wide, if the offset is the same, you'll likely have the same problem because it's the tire that rubs and offset is calculated from the centre plane of the wheel.

Cheers.