ok, 20s are prolly the most you would fit on a normal car, i say normal because impala's are pretty standard. i think you would have to get new suspention or maybe just get longer shocks for your suspention, i don' know to much about the impala so i could be wrong. i do also think, if u put 22's on that car ... it would adversly affect the handling sooo much that it just wouldn't even be worth it. i think 20's are to big but thats just my opinion.
so to answer your ?.... i don't think your could fit 22's on a 2007 chevy impala without moding the suspntion.