The front door speakers in your 1995 Nissan are four inches by six inches. The front dashboard speakers are 4.5 inches in diameter.
I recommend going Crutchfield.com as they have instructions on how to install speakers in most cars.
Answer 5 1/2 for the rear and 5 1/4 for the front.
The 2007 Nissan Altima has 42.2 in. of front leg room.
The 2009 Nissan Altima has 55.7 in. of front shoulder room.
The 2014 Nissan Altima has 54.0 in. of front hip room.
The 2002 Nissan Altima has 56.7 in. of front shoulder room.
The 2005 Nissan Altima has 56.3 in. of front shoulder room.
The 2002 Nissan Altima has 53 in. of front hip room.
The 2010 Nissan Altima has 40.6 in. of front head room.
The 2011 Nissan Altima has 40.6 in. of front head room.
The 2008 Nissan Altima has 42.2 in. of front leg room.
The 2009 Nissan Altima has 44.1 in. of front leg room.