I've never used an Austone.
42 will wear the center on a Cooper
40 will wear the center on a Goodyear
38 will wear the center on a Champiro.
On my Goodyear Assurance Triple Tred 205 60, 40psi throughout it's life (on my interstate) of 37 thousand miles saw it wear evenly across the tire. I have two other GATTs on both bikes at constant 40, and also have even wear. And I check them routinely too.
Just sayin'
I run 40. It does wear the center more than the outside tread but I prefer the solid feel. Any less that 40 lets her wobble a bit at speed in a curve.I can go down to about 38 with no symptoms, but much below that (just a few times) and I have had the
wallow effect too. Somehow it got down to about 30 once, and it slightly rubbed my swingarm too. No damage, and caught right away.