ST Tire "Plies" Question and a PSI Question

Carlisle Radial Trail RH are the new design they came out with a few years back. One of the changes and the hoopla at the time was the new cap on them. They also supposedly have some chemical in the rubber compound that reduces heat??? I have been running them since they first come out on my TT and so has my FIL on his FW and no issues. We have put many miles on them as well with biggest trip from Calgary down the Oregon Coast to California and back and not a glitch. Many smaller trips and all the local camping down the backwods gravel and so far they have done real well.

We both run them at the max suggested pressure as well even though I am closer on my C than FIL is on his D rating on his fifth. Better safe than sorry as they say.