ACR-X : Rear end slow to heat up

[schulmann]

We have a problem here with an ACR-X.
The rear end is slow to heat up on a given track. We ride this track in 3rd upto 6000rpm.
This is a very technical race track on concrete (Old Mirabel airport).


This is a "stock" ACR-X with Micheling slicks.
It is very well balanced and predictable.

Rear & front hot psi: 27

Didn't measure the tires temperature but by touching with my hands it was around 90-100F.

The front is very stable, holds and drivers like if it was following rails.
After 1-2 laps the front is ready: Brakes and Tires.


However the rear with the Michelins is "unstable" mainly because it takes 4-7 laps before the tires heat up so they get sticky.
Even after the rear tends to spin out in 3rd gear.

Is there an alignment for the rear so it gets more stable ?
What can be done to get the tires up to the right temperature ?