How many Miles + - does the grip last with New Tires?

I installed front and rear Pirelli Diablo Rosso II's yesterday,
had 10k on my rear Pirelli Angel and probably 4500mile on
the front Rosso II.

So...... a tad bit disturbing this am, disturbing
morphing into, 'nice'..... however the bike
DOES NOT turn well at all, which circles me back
to the operative; Disturbing.
I routinely do some quick shallow lane changes
when no one is on the road, and this am, given
very typical weather/conditions here, I
was taken back on how hard it was to change
directions at 50mph the bike felt like the
rotational inertia ( which makes some sense to me
given there is more rubber on these new tires)
was making the bike much harder to turn in in corners
and those lane changes I referred to, like the gyro
action is holding be back and almost as if there
is some braking action in play, though of course
I wasn't touching brakes.
-----------------------------
1. When does the excellent grip of tires like my
new set start to lose grip, is the compound markedly
different when we wear off 3/16'' of the new rubber,
1/8'' etc? More grip for that first layer of rubber
than underneath?
2. The grip feels really nice though and these tires
only have about 15 miles now, def not broken in,
on one hand I DON'T like the hard turn in action,
on the other hand, I'm really digging the nice grip,
but would like to get a 'grip' on roughly when
that grip will go away, as I realize its a very
gradual change and will be hard to gauge it, I'm thinking
that if I can get an idea of when that grip layer
is gone, when to expect it, I might just change
to a new set even though there is a ton or miles
left, and save them for burnouts etc.