輕型(xing)貨車(che)或面(mian)(mian)(mian)包車(che)用(yong)(yong)(yong)(yong)的(de)(de)(de)(de)輕型(xing)子午線載重輪(lun)(lun)(lun)胎(tai)(tai)(tai)都要(yao)(yao)在(zai)(zai)輪(lun)(lun)(lun)胎(tai)(tai)(tai)型(xing)號的(de)(de)(de)(de)后面(mian)(mian)(mian)加(jia)一個字(zi)(zi)(zi)母'C'，以(yi)(yi)便(bian)和(he)轎車(che)用(yong)(yong)(yong)(yong)的(de)(de)(de)(de)子午線輪(lun)(lun)(lun)胎(tai)(tai)(tai)加(jia)以(yi)(yi)區(qu)分。如(ru)(ru)(ru)：金杯面(mian)(mian)(mian)包車(che)用(yong)(yong)(yong)(yong)的(de)(de)(de)(de)輪(lun)(lun)(lun)胎(tai)(tai)(tai)185SR14C，其(qi)中的(de)(de)(de)(de)'C'即指此輪(lun)(lun)(lun)胎(tai)(tai)(tai)為(wei)(wei)輕型(xing)載重輪(lun)(lun)(lun)胎(tai)(tai)(tai)。而美(mei)準則規(gui)(gui)(gui)定：客車(che)用(yong)(yong)(yong)(yong)的(de)(de)(de)(de)輪(lun)(lun)(lun)胎(tai)(tai)(tai)，要(yao)(yao)在(zai)(zai)輪(lun)(lun)(lun)胎(tai)(tai)(tai)規(gui)(gui)(gui)格前面(mian)(mian)(mian)用(yong)(yong)(yong)(yong)字(zi)(zi)(zi)母'P'加(jia)以(yi)(yi)表示。如(ru)(ru)(ru)：切(qie)諾基(ji)用(yong)(yong)(yong)(yong)的(de)(de)(de)(de)P215/75R15輪(lun)(lun)(lun)胎(tai)(tai)(tai)，輪(lun)(lun)(lun)轂新(xin)報價，其(qi)中的(de)(de)(de)(de)'P'即指此輪(lun)(lun)(lun)胎(tai)(tai)(tai)為(wei)(wei)客車(che)用(yong)(yong)(yong)(yong)輪(lun)(lun)(lun)胎(tai)(tai)(tai)。有(you)(you)(you)很多(duo)駕(jia)(jia)駛員(yuan)不懂得這(zhe)個'P'字(zi)(zi)(zi)的(de)(de)(de)(de)含義，認(ren)為(wei)(wei)美(mei)國(guo)(guo)(guo)車(che)上就(jiu)(jiu)必(bi)須(xu)使(shi)用(yong)(yong)(yong)(yong)帶'P'的(de)(de)(de)(de)輪(lun)(lun)(lun)胎(tai)(tai)(tai)，因(yin)此，在(zai)(zai)換輪(lun)(lun)(lun)胎(tai)(tai)(tai)時沒(mei)有(you)(you)(you)'P'字(zi)(zi)(zi)的(de)(de)(de)(de)輪(lun)(lun)(lun)胎(tai)(tai)(tai)不敢(gan)使(shi)用(yong)(yong)(yong)(yong)，經常鬧出一些笑話。有(you)(you)(you)些輪(lun)(lun)(lun)胎(tai)(tai)(tai)經銷(xiao)商，在(zai)(zai)遇到有(you)(you)(you)這(zhe)種心理的(de)(de)(de)(de)駕(jia)(jia)駛員(yuan)以(yi)(yi)后，便(bian)把帶'P'字(zi)(zi)(zi)的(de)(de)(de)(de)輪(lun)(lun)(lun)胎(tai)(tai)(tai)價位賣(mai)得很高。其(qi)實'P'字(zi)(zi)(zi)只是美(mei)國(guo)(guo)(guo)的(de)(de)(de)(de)一種規(gui)(gui)(gui)定，比如(ru)(ru)(ru)，我國(guo)(guo)(guo)上海回(hui)力輪(lun)(lun)(lun)胎(tai)(tai)(tai)廠生產的(de)(de)(de)(de)輪(lun)(lun)(lun)胎(tai)(tai)(tai)185/70R14輪(lun)(lun)(lun)胎(tai)(tai)(tai)，要(yao)(yao)出口美(mei)國(guo)(guo)(guo)給福特(te)廠生產的(de)(de)(de)(de)天霸(ba)車(che)配套使(shi)用(yong)(yong)(yong)(yong)，那(nei)么，根據美(mei)國(guo)(guo)(guo)的(de)(de)(de)(de)規(gui)(gui)(gui)定，上海回(hui)力廠生產的(de)(de)(de)(de)185/70R14輪(lun)(lun)(lun)胎(tai)(tai)(tai)的(de)(de)(de)(de)前面(mian)(mian)(mian)就(jiu)(jiu)要(yao)(yao)加(jia)個'P'字(zi)(zi)(zi)，以(yi)(yi)示此輪(lun)(lun)(lun)胎(tai)(tai)(tai)為(wei)(wei)客車(che)用(yong)(yong)(yong)(yong)輪(lun)(lun)(lun)胎(tai)(tai)(tai)。

由(you)于(yu)子(zi)午(wu)線(xian)輪(lun)胎(tai)(tai)與“扁(bian)平(ping)(ping)形輪(lun)胎(tai)(tai)”的(de)(de)問世，輪(lun)轂(gu)電話咨詢，便(bian)出(chu)現了新的(de)(de)輪(lun)胎(tai)(tai)尺寸參(can)數(shu)(shu)符(fu)號。美、日(ri)等國家(jia)現采用輪(lun)胎(tai)(tai)尺寸系列就是以高寬(kuan)(kuan)比（H/B）作為(wei)輪(lun)胎(tai)(tai)分類基(ji)礎(chu)的(de)(de)，稱(cheng)為(wei)“扁(bian)平(ping)(ping)率”。子(zi)午(wu)線(xian)輪(lun)胎(tai)(tai)規格的(de)(de)表(biao)示方法(fa)是把(ba)標(biao)志子(zi)午(wu)胎(tai)(tai)字(zi)樣的(de)(de)“R”置(zhi)于(yu)斷面(mian)(mian)寬(kuan)(kuan)與輪(lun)輞(wang)直(zhi)徑(jing)之間。如型(xing)號185/60R14，其(qi)含義自左至右(you)：數(shu)(shu)字(zi)185表(biao)示輪(lun)胎(tai)(tai)寬(kuan)(kuan)度185mm，符(fu)號“/”后面(mian)(mian)的(de)(de)數(shu)(shu)字(zi)60即扁(bian)平(ping)(ping)率為(wei)60%，輪(lun)轂(gu)現貨，字(zi)母(mu)“R”表(biao)示該輪(lun)胎(tai)(tai)為(wei)子(zi)午(wu)線(xian)輪(lun)胎(tai)(tai)，后一(yi)個數(shu)(shu)字(zi)表(biao)示輪(lun)輞(wang)的(de)(de)直(zhi)徑(jing)為(wei)14in(356mm)。

作為(wei)輪(lun)(lun)(lun)胎簾(lian)(lian)(lian)(lian)(lian)線(xian)(xian)用(yong)的(de)(de)纖(xian)維，輪(lun)(lun)(lun)轂(gu)，早用(yong)的(de)(de)是棉(mian)線(xian)(xian)，1935年(nian)(nian)(nian)人造絲(si)(si)簾(lian)(lian)(lian)(lian)(lian)線(xian)(xian)開始被采用(yong)。人造絲(si)(si)簾(lian)(lian)(lian)(lian)(lian)線(xian)(xian)輪(lun)(lun)(lun)胎在耐久性方面優于(yu)棉(mian)簾(lian)(lian)(lian)(lian)(lian)線(xian)(xian)輪(lun)(lun)(lun)胎，所以(yi)人造絲(si)(si)簾(lian)(lian)(lian)(lian)(lian)線(xian)(xian)很快(kuai)取代(dai)了棉(mian)簾(lian)(lian)(lian)(lian)(lian)線(xian)(xian)的(de)(de)地(di)位。繼人造絲(si)(si)之后(hou)，尼龍(long)于(yu)1950年(nian)(nian)(nian)前后(hou)開始普遍應用(yong)于(yu)轎車輪(lun)(lun)(lun)胎。由(you)于(yu)尼龍(long)簾(lian)(lian)(lian)(lian)(lian)布能大(da)大(da)延(yan)長輪(lun)(lun)(lun)胎的(de)(de)使用(yong)壽命，故20世紀60年(nian)(nian)(nian)代(dai)尼龍(long)簾(lian)(lian)(lian)(lian)(lian)線(xian)(xian)已(yi)在某些國家的(de)(de)輪(lun)(lun)(lun)胎工(gong)業中占據主導地(di)位。人造絲(si)(si)簾(lian)(lian)(lian)(lian)(lian)線(xian)(xian)用(yong)量已(yi)明顯減(jian)少，棉(mian)簾(lian)(lian)(lian)(lian)(lian)線(xian)(xian)已(yi)基本被淘(tao)汰。1962年(nian)(nian)(nian)聚酯簾(lian)(lian)(lian)(lian)(lian)線(xian)(xian)投人工(gong)業生(sheng)產，此后(hou)無機質的(de)(de)玻璃纖(xian)維、鋼(gang)絲(si)(si)等(deng)也(ye)先后(hou)被投人使用(yong)。