I Suspect The Bridgestone Exeda G851 130/70r18 Defective After 5000 Miles

I installed (1) Bridgestone Exeda G851 130/70R18 to the front of my customer's 2010 Gold Wing trike at 22,000 miles. They now have 27,289 miles on the tire and it has defective ½"-1" cracks in tread grooves but only on (1) side of tire. There are (2) different tread groove types radiating out to and along each side of the tire but only (1) type (and every one of that type) have the ½"-1" cracks. Please see attached pictures. The bike is always garaged. Owners are mature seasoned riders in their 50's I have ridden with the past 8 seasons. Their motorcycles are well maintained either by their dealer or locally by me. I am a mfg. Engineer who has owns, repairs and rides motorcycles since 1967.The owners experienced a complete loss of air in local parking lot recently. They aired tire up but wouldn't hold. They installed tire sealer and tire is holding air so far. I advised them the tire is not safe to ride and to park it until tire issue is resolved with aftermarket motorcycle supplier J&P.I chatted with J&P's customer service person who recommended I, "call J&P customer service to be setup with returning tire & to answer questions mfr. wants answered." They said that a Returns Specialist looked at it & thought it was "dry rot." Returns Specialist discussed w/ his manager. The manager said there was "nothing they could do regarding dry rot after 120 days." I don't agree that a tire owned, ridden and cared for, like this one, has "dry rot" at 5000 miles. Especially since the defect shows as a definite and pattern on only (1) side of the tire. Please advise and best regards,Timothy PrushaPrusha Motor Company