I was giving the car the once over on a few things & thought I'd also check the air in my trick tires. I noticed the passenger rear was way low,<15 psi when checked. The tire was on the blind side of being seen normally. These are Destination A/Ts by Firestone, low miles. I looked over the tire & didn't see anything. Then I rolled the vehicle some & hidden on the bottom was a roofing nail in all the way. I remembered a 'plug kit' my brother had given me years ago. I read the directions & removed the nail & 'plugged' it. So far,so good, much quicker & easier than my usual of taking the tire off & bringing it in. I'll keep an eye on the psi for awhile. Just a reminder for you 'DIY' guys.
Still holding just fine, 24 hrs later.