If you run hard enough, you would have beated up the center of your tires at that PSI.
I run AD08's on my Porsche, IMO you should have kept them in 36-38 psi HOT. Once they get over 39 40 psi, they start losing grip and make you feel like driving on skateboard.
Build #1 NA: Big Willow 1:30.449 (NT01), Buttonwillow 13CW 1:56.634 (NT01), Autoclub Speedway Fontana 1:49.422 (NT01), Mfest2012 LMVS 1:59.002 (NT01+AD08), Streets of Willow 1:22.36 (RS3), Chuckwalla 2:02.46 (RS3), Laguna Seca 1:41.74 (R888), Infineon 1:50.346 (R888)
Build #2 VF SC: Buttonwillow 13CW 1:54.037 (TD), Big Willow 1:29.63 (R888)