There is nothing wrong with 16inch wheels. And 7inch wide rims means that peterdep could fit wider 225/50R16 tyres. The advantage is a better ride and less tendency to be knocked off-line by mid-corner bumps.

The issue is the offset: At 40mm it isn't enough as stock is 55mm. peterdep might get tramlining problems and the tyres might poke out beyond the mudguards. The other thing to check is if the brake calipers will fit inside the rim.

Also, I don't think that Tirerack freights to OZ anymore.