打呔氣 tyre air pressure - part ii

除左跟番汽車標示上既呔氣, 另一樣野就係睇下打的咩氣入去.

其實我地呔鋪都係打空氣入去 (先聲明左先) , 同油站個的打呔氣既氣都一樣.

有的呔鋪 / 車行就打氮氣 (Nitrogen) 入去.

兩者分別在於, 打空氣入去, 呔既氣溫上升時, 空氣因氣溫上升而脹左. 令到你既呔氣都會大左(壓力). 

最好打氣既標準, 就係行完車睇下呔氣升左幾多. 如果本身要打32psi, 原先有打左32psi 的話, 已行完車之後升到上35psi 既話, 咁可能你會想放番的氣到29psi / 30 psi. 行車時就會行番32psi 啦.
(再睇番個post 發現原來我打錯, 一定係最近太熱, [幫自己搵緊excuses ><] ) 最好打氣既標準, 應該係條呔唔熱(正常溫度)既時候, 打番個個氣壓. 如果標籤寫32psi 的話, (而條呔係正常溫度下), 打番32psi.


而再詳細的更標準既係, 唔同溫度應該打番唔同既汽壓, 如夏天, 就會打32psi, 冬天打少的咁之類既野, 但係避免咁煩, 都係未開車之前打番個標準氣壓, 或者係開車後隔一陣先再打. (如果趕時間等唔到條呔cool down 番, 直接打32psi 或打多少少)

打32psi 即係最底既呔氣壓, 都係車廠建議的. 但係我又覺得奇怪, 又冇講到係用氮氣做標準, 定係普通既空氣做標準. 係咪因為太複雜, advise 人地打最底既呔氣壓?

(有少少緩衝都冇問題既)

其實冇乜人check 到咁嚴既, 只要行得好就冇乜所謂. 不過氣壓太多既話除左部車會彈下咁之外 都有機會"省"兩邊呔的 (下次再講)

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To be more professional, it's important to check what type of gas is pumped into the tyre.

Actually our store pump normal gas into the tyre  (For your information) , the same as gases used in the petrol station.

For some tyre store / car maintenance company, they pump in Nitrogen

The difference is that Nitrogen is not easily affected by the temperature, but normal gas's kinetic energy increases when temperature increases. When tyre temperature increases, air pressure in the tyre increases as well if you are using normal gas. 

The best way of ensuring the standard of air pressure, is to check how much tyre pressure increases after you started your car and drive for some time. If you are supposed to have 32psi for your tyre, and you have already pumped in 32psi at the beginning, the tyre pressure increases to 35 psi after driving, then you may want to release some of the gas in the tyre to 29 / 30psi. 

(Revising the post and found out that I had written wrongly about the tyre pressure. It must be the heat!! [ Finding excuses for myself >< ]) The label on the car indicates the tyre pressure in cold temperature. If the label states 32psi, then it's recommended to pump in 32psi under normal temperature (which I assume is room temperature and pressure)

There is actually a complex matrix to tell drivers how much tyre pressure should be pumped in under different temperature. E.g. pumping in 32psi during summer, and a little more psi during winter.

To avoid complication, simply pump in the recommended tyre pressure on the label when the tyre is not hot would be good enough for most of the drivers. (If you don't have the time to wait for the tyre to cool down, just pump in 32 psi, or a little more would be fine)

In sum, 32 psi (in this example) is the minimum tyre pressure you should pump in. Car manufacturer did not mention the best tyre pressure when the car tyre has "warmed up", and did not state whether to use Nitrogen as standard, or normal air as standard. Perhaps it's too complicated to involve in tyre?

(a little buffer should be fine for your driving)

Actually we don't really have to check so serious that we have to follow the rules as long as it does not affect our driving. However, if you pump in too much air, not only if you feel your car is "jumping" kind of feel, your tyre tread may worn off easily at two side (which I will talk about in the next part)