how would set like that do on a 16x7 rim?

225's are a bit big for 7" rims.  The biggest you would probably want to go is 215.  Otherwise your handling will suffer b/c your sidewalls will look like this...
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ewwwww we wouldnt want that! lol thanx man, i think maybe i'll go 215 40 16 or 205

215 should be about right.  205 would work, too...probably better.  Let's see...If I remember correctly it goes like this...
6.5"---185,195,205
7.0"---195,205,215
7.5"---205,215,225
8.0"---215,225,235
and so on
that's with the middle number being ideal, the left a tad small, and right a tad big.