Eeeks MD. Any remote signs of rot on a 7 year old tire?

I've always been replacing our 275/315 in random like it's going out of style. Either due to potholes (one year I got 3 sidewall blowouts over the course of 2 weeks right post winter).

I've got a slow leak on a 315 right now....and can't find a nail/protrusion anywhere. Just give it some 02 every 3 weeks