I also carry nothing. Thought about a spare for long trips but so far haven't done the research.
I have been on runs out to Bathurst and back a few times and down to the snowy mountains a few weeks ago and - touch wood - no problems.
I did however invest in a tyre pressure monitor from TyreDog, picked it from Repco during the sales for $150! RRP is $399.
It works great and every time I fill up I can just check the LCD screen to see if tyres need a top up.