I own a Sport, not as heavy on the front as a Turbo but what should the tyre pressures be. 205x40x17, tyre wear is only on the edges not the middle - front, rear okay, booked in at TSL on the 19th for geometry set up

 

Not sure exactly what you should use, (other than air) but it sounds like they're a bit low!

 

I used to go with 32 F, 30 R. on my sport. wear was even.
As you know, will also depend on your driving style
My bridgestones RE720's lasted over 30k (on 15's tho).
I spose as a rule of thumb, more pressure = more wear in centre.
Less pressure= more wear to edge.
Find the happy medium for your tyres, you will also notice the handling will change , as you go up or down the pressures.