Later, with American technology unavailable, he spent five years working to overcome all manner of technical difficulties, finally lowering the failure rate of his tires from 30 % to 2 %.
之後在美國技術保密的情況下，他又費盡周折，用了 5 年時間，使汽車輪胎的合格率從 70 % 提高到 98 %。