I am reporting a potentially serious and widespread safety defect involving Goodyear Wrangler TrailRunner AT tires installed as factory equipment on General Motors trucks. My 2025 GMC Sierra 3500HD Denali has just 5,800 miles. Both rear tires, with DOT code 2724, have developed identical sidewall bulges behind the “NER” in the “TrailRunner” stamp. These bulges are consistent with internal structural failure, not road hazard damage. The truck has never struck a pothole or curb, and there is no evidence of impact or external damage. I have personally inspected several brand-new GM trucks on dealer lots, equipped with the same Goodyear tires, showing the exact same sidewall bulge in the same location. These trucks also have newer DOT Manufacture date stamps. Most importantly, these vehicles have never been driven, which strongly suggests a tire manufacturing defect, not a driver-related issue. At my first scheduled service, the dealer’s service department refused to rotate the tires, citing the bulges as a safety risk. I filed a formal complaint with GM and requested that they involve Goodyear. GM denied the request, claimed the damage was from road impact (without evidence), and stated that the decision was final and not disputable. They refused to conduct any further investigation or escalate the claim. I believe GM’s refusal to act on a potential structural defect, especially one seen across multiple new vehicles, demonstrates a failure to exercise due diligence and exposes the public to unnecessary danger. A blowout from these bulges could lead to serious injury or fatal crashes. I am urging NHTSA to open a defect investigation into Goodyear Wrangler TrailRunner AT tires, particularly those with DOT code 2724 and newer, as installed on GM trucks. I am prepared to submit photographs and dealership documentation as necessary.