請勿灌水。

我是s2.0的focus-手排 ! 有裝st 18吋的鋼圈及胎!  我覺得還okㄝ! focus st應該更不是問題! 當然有換輕量的!真的應該差很多!

oh...列寧終於問了一個比較可以計算的問題了~

就以你的數據來說,四顆8.5KG和四顆12.5KG的輪胎,然後車子總重不同ooxx...

先說抱歉,我這邊沒有ST的車主手冊,所以除了輪胎重量的假設之外,先用S2.0數據來做計算

S2.0引擎的最大出力為109KW,當然大家都看過馬力圖,不可能一開始就是最大值,

所以,我假設一檔加速2秒可以到最大轉速109KW後需要換二檔,一秒算平均55KW好了

A組總重75KG*3+1350KG-16KG=1559KG

B組總重75KG+1350KG=1425KG

再假設兩個圓柱(輪胎)的寬度和高度都一樣,所以用205/50R17的輪胎,

I=1/2 m( R2 /4+ L/12),其R為17*2.54+20.5*0.5*2=63.68cm=0.6368m  L=0.205m

所需能量為P=1/2Iω^2 又角速度ω=V/r  注意V算出來是m/s,所以要x3.6換成KPH

所以A組的速度為55*1000=0.5*1559*V^2+0.5*8.5*[(0.6368/4)^2+0.205/12]*(V/0.6368)^2

55000=779.5V^2+0.445V^2   V小算盤算出大約為30.230954273062448132289662357439 KPH

而B組的速度,帶入同樣的公式後   55000=712V^2+0.655V^2

V小算盤算出大約為31.626004088686720178755848969447 KPH  看到了嗎?B組快多了,

前面重量比例差太多了,後面因為輪子的轉動慣量的差別,只有0.445和0.655的差別而已!

所以,不要想太多了...

不要想太多是指什麼？

你用ST的車重來計算好了，
輪子的重量一樣，
ST車重原廠說是1480，
A車輪下每輪少4公斤，也就是8.5公斤。
B車輪下是原廠設定，12.5公斤。
問題如下：
1.假如兩車都是75公斤的人開，試問結果？
2.輕量化的A車，是100公斤的車手，B車是60公斤的車手，試問結果？

物理方面的試算題 麥克胡 最喜歡也最擅長了..

麥克胡!請解答..................

我有4柯18的...9.5公斤

其實我只是為了視覺效果
我不飆車的啦

我摘我摘........

開很快ㄋㄋ......

Leinin,

This topic has long been debated. Two things are your main consideration when it comes to selecting wheels.

1.Weight

Lighter wheels tend to tramp less (lower unsprung weight) and offer optimum road contact. The result of the improved road contact allow higher cornering forces with greater reserves of safety, improved handling and a better ride comfort (under the same size of course). An important benefit, particularly in the case of large vehicles, is the excellent brake ventilation and therefore, improved braking characteristics.


2. Strength

Lighter wheels tend to be weaker in comparison and are more prone to road damages. The solution is to use the better engineered wheels or forged process. Some wheel developments use design to achieve weight reductions. The equal distribution of the better designed wheels allow forces to be transferred perfectly to the centre.  And in theory, forged process makes wheels much stronger and resistance to bending in comparison to other cast counterparts.

Depending on the person who is making the decisions, everyone has different needs. Some enjoys the benefit of good quality lighten wheels and say they are a must. However, they are far more expansive in general.  For those just after the look and not going to bother with the wonderful quality roads of Taiwan, then normal sets of cast wheels should do just fine as they are far less in cost. Another word, use your money somewhere else, say your girlfriend's PRADA handbag or something.

Hopefully this answers your questions.

Howard