I'm surprised that you run 3 degrees neg all round , yet tyre temp's are even across the inner/centre/outer tread but the tyre in your photo has centre wear greater than outer tread. You don't mention inner tyre tread wear
If only the centre tread has higher wear then that would indicate too much pressure , probably around 2 psi . If the inner tread wear is similar to the centre tread wear , then I'd assume too much neg camber -- I'd try 0.5 degree less then work towards the best setting.
Regarding the 3 degrees all round --- what spring rates do you run and is that without anti-rollbars at either front or rear

car weight
PM me for email direct chat if it suits .