Both of those tire sizes are shorter in height and not as wide either. I would stick with the same tire size but switch to a different tread pattern. I have never liked how the Toyo Open Country A/T's have performed in the rain.
For my Rebel owners who have wanted to switch tires I have recommended either the Yokohama Geolander H/T's or the Bridgestone Dueler H/T's. They are not the aggressive tread pattern of an A/T tire but they ride great and handle well in the rain and snow.