Clive, if you change tyres, you might as well change all 4. I timed pitstops in earlier events, and there's no time saved by only changing one axle - in fact, it may take longer, since you have to actively deselect those you won't have changed.
Setup wise, my setup here differed greatly from the one used for our first oval race. For that I did all sorts of experiments with asymmetrical setups, with firmer righthand side settings, but eventually only the tyre pressures were asymmetrical - all suspension settings were set as soft as possible, as that was quickest for me.
Used that as a base for this race, but quickly discovered that firming up the righthand side settings made me faster, so ended up with very soft left side and very hard right side. When driving, I braked lightly, very deep into the corners, when coming from the long straights. No other 'secrets' to my laptimes, but you're probably better off asking Ziu how he achieved his times..
Cheers,
Erling