For myself I feel more comfortable lowering the pressure with plenty of sidewall. If traction really sucks I can go down to 10 lbs psi and let that sidewall get wide with no worries.

I wouldn't do that on low profile hard sidewall DR's. Just my opinion. Now MDSRT6 did run the same hoosiers on his stock 19's and had plenty of success. Not sure how low he lowered the pressure. I can tell you from experience I have ran qualifying passes at 35 lbs psi when the track is prepped nicely and still cut 1.7's 60' times. For consistency I always have my pressure around 15psi.

When I drove the E55 which had Nitto 555's, I lowered them to 17 psi and ran an 11.88. I don't recommend doing that very often.