Normally, the new tires plus rims should not be more than +/- 3% of difference compared with the factory tires+rims. Otherwise, you could be caught by cops for speeding although your speedometer is says legal speed. Conversely, you might drive at <<100 km/h blocking up traffic although your speedometer suggests you are driving at a nice speed of 100 km/h :-) :-)
就个人经验,轮胎店和Costco都只推荐原厂尺寸。可以直接打电话给dealer,也可以自己上tire rack 网站查,输入maker, model and year, 选择tire/rim package, 就能看到不同的组合了。我的车原厂是18寸,冬胎就选的17寸,会便宜一点。轮胎直径大了1%,开起来没有区别。
在轮毂不被刹车挡住装不下的情况下,我推荐冬天用小一号的轮毂,轮胎外径正负3%之内,轮胎换窄一到两号(如果轮胎load rating允许)。这样做的优点有几个 0 W2 _6 h1 a) F$ D, h, V. O1、轮毂轮胎都小了,整体都便宜 % a. t" r5 q! E. X2、轮毂小了,外径没变,这样侧壁占得比例多一些,冬天会感觉更软,过大的pot hole或者撞curb有侧壁保护6 ^) ?* f( g6 V) z/ x: u
3、轮胎接触面积(contact patch)小了,牺牲一些在干路上的性能(冬天本来就开不快,而且冬天干路比较少见),冰雪性能强了很多。3 u$ L6 j: l. k' ? `( I8 U2 n" E
2 M, j& h+ S7 G3 ~0 b开过一辆中型SUV配原厂尺寸冬胎的例如255 55R18,感觉像是在滑雪或者冲浪。也开过同款车,轮胎故意缩小到235 65R17,就像完全不一样的两辆车。我自己的车原厂215,冬季用205,夏季用245.