You can not translate "housing's edges" by itself, since "wheel housing" is a compound word, and it means the room where wheels/tries are installed in a car, motorcycle,etc. see the first link below.
So, "filing wheel housing's edges" means smoothening the edges of this container where the wheel is installed.

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Note added at 6 hrs (2011-02-19 21:03:18 GMT)
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That is why the Arabic translation I posted above (حواف تجويف الإطار) is equivalent to "wheel housing's edges" and not merely to "housing's edges".