It's generally recommended that you don't go more than 15mm wider than the underfoot width of your ski. I'd reccon you could probably get away with it though, my dad being a cheap ass threw some brakes on his skis that were 24mm larger than the underfoot and he skied them fine no problem.
My UK/EURO BST Thread - http://www.newschoolers.com/ns/cult/forumthread/thread_id/743385/
Check my blog for updates and reviews: http://aslansskiblog.blogspot.co.uk/
Joey -Formerly *III.JVD.III*
I post from mobile the majority of the time, so if the above is incomprehensible, I apologize.