NEW: just read end of the thread
OLD: I think, it would be nice, if water tankers were also counted as firetrucks.
When you have mission and need e.g. 3 firetrucks and you send 2 engines and water tanker, it is not enough, because tanker is not "firetruck".
It will be usefull mainly for Europe players, where tankers respond to most fires, because we don't have very good fire hydrants network. Tankers often respond to "small" fires like car fires etc.
And there is tanker at almost every station. About half volunteer fire departments have only one truck - water tanker.