What waist width for snowboard?

I'm lookin at gettin a new board for this season and am wondering if i need a wide board. im intermediate and ride both groomers and park/rails.im lookin at gettin the forum grudge but cant decide to get the regular size waist which is 250mm or the wide which is 255mm. also the rome slash which is 258mm. i have size 11-11.5 boots