225-15's on a Carson 7k trailer? Will they fit?

[Waterman]

I have a 16ft. Carson Flat Bed (same as the standard car hauler without the dovetail.  Came with 205 / 75 / 15's and would like to upgrade to 225 (can't seem to find a 215 in 15").  Has anyone put this size tire on the stock wheels on a Carson?  Short of loading up the rig and tring to find some way to stuff one tire there really isn't an easy way to see how far the double axle set up stuff's into the fender.  Any info would be appreciated....Thanks....Bob