Clutch was replaced in my 2005 nissan micra about 3 months ago, today I inflated my front tyre to specification pressure (2.3 bar) and immediately after driving I felt something was broken so I checked and the top supportive bracket for the tranmission had completely snapped leaving the engine and tranmission drooping far down under it. What could have caused this? Could the increased tyre pressure have forced it to snap due to its age or was it really just a coincidence?
No the transmission bracket do not break as a result of changing tire pressure.
It is more likely this is a result of not properly adjusting the engine mounts and transmission bracket when your clutch was replaced,or the engine mounts might have started to fail as a result of wear.
I think you should take a look at the engine mounts to see if the rubber is damaged and they needs to be replaced,the transmission bracket might get overloaded if the engine mounts starts to fail.