2018 Toyota Highlander

These are Toyo Open Country P245/55 R19 tires that have been on my car from 10/23/2020 to now and have 54,600 miles on them. Remaining tire tread depth on this tire was measured using a machinists rule at 6/32" or 4.5 mm deep. The drivers front tire looked fine on my car during a general pre-inspection I did at 6:45 AM as I loaded the car with our luggage for a 7 day drive trip to Florida (app 920 miles). I will advise that I did not look at this tire in great detail during this check - just quick look to see if anything stood out that I needed to be concerned about for the drive. The drivers side front tire went flat after backing straight down a 60' long driveway. I removed the tire with the car in the street and took it to the tire shop where I bought these tires. The tire shop guys found several cracks about 1/2" long or longer in this one spot in the tire sidewall at the start of the tread. They had no idea why it cracked like that and had reported that they had not seen cracks like that in that location before in any tire. I had them pull the tire off the rim and put a plug/patch in it so I could get the car back up the driveway to repack our Florida luggage in the other car. No other tires show this cracking issue. I will replace the tires on 9/11/2023 with new tires. The tire could have blown out on I-10 at speeds of 70-75 MPH due to the almost immediate loss of air pressure due to the crack. There was absolutely no indication of any issues with this tire (or the other 3 tires) prior to backing down the driveway and the tire going flat. I was blessed that the tire lost pressure quickly just backing down the driveway and not on the Interstate highway. I drive the car - no one else. The tires have not been abused during the period they were installed. I rotate the tires every 10,000 miles. I do car PM on a 6 week schedule to avoid any such auto issues. I had just completed a PM about 1 week prior to this tire issue with all found OK.