oh man. i had this long reply typed out and it error-ed out. ok, dude i really think that people just as easily could answer the question as flame you for asking it, but thats another story.
what you need is a chart for converting stuff. with 31s you will run 2085 rpm @ 55 and with 33s it goes to 1960. thats with 3.55 gear ratio. also, i just found that with a little conversion program i found here
http://www.4lo.com/4LoCalc.htm and i found that by entering "gear ratio,tire size" in Yahoo search. "what size tire can i run" has to be the oldest most asked question besides "how much lift do i need to run" ... either way, i do think jumping newbies cases isnt cool to a certain degree, but i understand why people do it. my pet peeve was when there were two threads going about what welder to buy and a guy asked a third... dude. the other two threads were still on the first page of the forum. still with as many members as we have & as few that vote & visit regularly, i think they get scared away. get a 78-9 & 460, run what ever you like.