This technical telemetry report examines tire production batch 1521, manufactured during the 15th week of 2021 (April). Operating at a calculated age of 5.3 years, the structural integrity and polymer elasticity of this serial series have been evaluated against NHTSA and NASCAR safety benchmarks.
Pit Assessment: Rubber is entering mid-life aging. Inspect sidewalls for micro-cracks and check tread depth.
"Stamped with serial 1521 (April 2021), this tire is entering its mid-life phase at 5.3 years of age. While functional with sufficient tread, natural atmospheric oxidation has initiated plasticizer evaporation. Sidewall flexibility is reduced."
Cross-reference batch age with standardized grading for rolling resistance, wet grip index, and pass-by exterior noise.
If inspecting a pre-owned vehicle fitted with DOT 1521 tires, note that you are looking at rubber manufactured 5.3 years ago. Because the rubber compound has hardened, request a tire replacement credit or discount from the seller.
Found DOT 1521 on your emergency spare? Unused rubber still oxidizes due to ambient temperature swings and ozone in the trunk. This spare remains safe for standard emergency highway use.