I don't know how it is in Australia but in west Texas you don't want to be without a spare tire. It could take hours for service; you do not want to sit in sun at 100 degrees plus Fahrenheit. I currently have 20inch wheels on a GLC 300 that came with run flat tires. I had to replace them at 20,000
miles I replaced them with Michelin Pilot all season tires non run flats. The Michelin performed well double the milage 39,000 miles
currently on my second set of Michelin Pilots. I did purchase spare a wheel on eBay. The spare wheel does takes up lots of space I only take it on long trips.