The edge wear is well known, this was a problem on the S version, the R was supposed to cure this but it's made it worse.
Putting 40 psi in may save a little edge wear but lose you masses of grip esp in the wet.
The profile will not cause accelerated wear, but obviously lower profiles are usually destined for more powerful cars, so will most likely be a softer tyre anyway.
I got 16,000 from the T1S on the astra, then when the T1R's were put on this dropped to 6,000, that's the last time I used toyo, NOTHING was changed on the astra.
Try some Hancook V12 Ventus Evo, awsome tyre, running these on the sapphy.
tabetha