Got just 4 1/2 miles from home - had just started up Mt Roubidoux when i noticed the rear tire was kind of squishy. Bounced my weigh on it and heard and felt the rear rim bottom out on the sidewall of the tire. Pulled over amd checked for thorns. Nothing. Figured maybe if i aired it back up to 70 psi i could make it back home before it was flat again? Upon removing the tiny electric pump hose the valve core blew out! As a lifetime cyclist and former Pro Shop Service Manager and Mechanic i happened to bring along a valve core tool and resecured it… and aired it back up. I got down to the street below the mountain and it was bottoming out again! Never heard any hissing. Flipped the bike, pulled the tube, ran my hand arousd the inside of the tire and nothing! Replaced the tube. Began the reinflation process and again the valve core blew out! At that juncture, an aged fella came walking up lighing a cigarette amd engaged me in conversation as I reinstalled the valve core and attempted to reinflate the tube - tire again. The electric pump runs out of power at 30 psi and as I remove the hose, the core blows out again! As i resolve myself to the idea that i was facing a 5 mile walk home in cycling shoes or do i call my mother in law for a ride? The gentleman sitting at the concrete picnic table with me says; “Would you like a ride home?” I responded; “Actually that would be wonderful!” Asked him what hes driving and he pointed to a brand new Hyundai SUV! I said that will accommodate the bike easily! And so here i am back at home in time enough to go fetch my wife from her work… For Sale: One brand new $120 electric mini pump and I’d recomment not buying poly tubes witb plastic valve stems. Most makers are switching to aluminum I’ve come to learn already. Apparently thr heat generated in electric mini pumps just compressing the air makes the air hot enough to almosy melt the plastic stems and possibly the tubes where thr valve attaches to thr tube! What a cluster? Fortunately I have a supply of both buytl and poly tubes to hold me over until the aluminum equipped units come available in the US later this summer. I’m grateful for the “Angels in the Outfield” today 🙏🏾🫡🚴🏾👁️🏔️