OB owner manual上用的是"You must"。必须保证四轮是同样的size, circumference, construction, manufacturer, band, tread pattern, degree of wear, speed symbol and load index。否则不只是power train的问题,会影响操控和制动性能,换 句话说是安全隐患。刚去翻了翻yaris的owner manual,用词是"do not mix ... tread pattern or tread wear",否则lead to fatal or injury accident。