On March 30, 2023 I had my winter tires and wheels changed out for my summer tires and wheels Goodyear Eagle F1 Asymmetric 3 in sizes 265/35ZR21 101Y XLand 305/30ZR21 104Y XL. At the time, I had about 25,000 miles on the car, and perhaps 15,000 miles on the summer tires. The tire inspection report from Porsche indicated that I had acceptable tread depth on all tires, and no unusual treadwear. Around the end of June I started seeing a very slow pressure decrease in my left rear tire, from about 41psi to 38 psi over a few weeks. On July 18, I experienced a severe drop in pressure to 22 psi and I filled the tire with air to 45psi and used the tire sealant to drive the car to the Porsche dealer, and arrived with 29psi. At no point during the time I had the summer tires on did I ever do anything unusual, or hit any road hazards. Porsche provided me the attached video showing severe cracking between the sidewall and tread around the entire diameter of the drivers side rear, and cracking around part of the diameter of the passenger rear. They claimed this was due to 'misalignment' of the rear tires. The alignment report (attached) shows the drivers rear was within specification, and the passenger rear was 0.2 degrees out of camber (-1.8 deg vs spec of -1.6 deg). There was still 4mm of tread on the tire, and no unusual tread wear was noted on any tires. I have replaced all 4 tires, and am very concerned that the same thing may happen, and I could have a catastrophic failure at high speed. Porsche is unwilling to do anything other than pay for the drivers tire. I don't see how I can be assured that the exact same thing won't happen in the future, since there was no testing or observation that Porsche did that indicated any kind of problem.

- Cincinnati, OH, USA