This research quantifies lead-time elasticity—the degree to which safety stock buffer requirements respond to lead-time variability—and demonstrates how systematic buffer optimization improves supply chain performance in Tier-1 automotive suppliers. Analyzing 80 automotive component suppliers in the Pune cluster, the study establishes a mean lead-time elasticity coefficient of $1.79 \pm 0.25$. The research demonstrates that by reducing lead-time variability and implementing optimized buffering strategies through the DMAIC (Define, Measure, Analyze, Improve, Control) methodology, suppliers can achieve a 30.7% elasticity reduction, a 13.6% safety stock reduction, and an 8.80 percentage point improvement in On-Time In-Full (OTIF) delivery. Lead-time variability exhibits a strong negative correlation with OTIF performance ($r = -0.917,

< 0.001$), indicating that elasticity management directly impacts supply chain reliability. The integrated DMAIC-SCM framework enables suppliers to balance inventory investment with service levels, reducing stockout incidents by 35-45% and improving inventory turnover by 15-20%.