This should also fit the firebird in 235/75 15 size--should fit a 15x6,7,8 rim: Which generation firebird?
http://www.maxxis.com/AutomobileLigh...ot-Mudder.aspx
Note that i don't know jack about 4x4/off roading etc., but i've heard/read good things about the buckshot radial mudders. Plus, just looking at them they seem very serious.
Will provide more info i have time, which i may not.
Update: ok i saw you have a 3rd gen firebird, this should still fit, but you realize that the bolt pattern is different on the wagon?