Depending on fitments, I will be going with 18 x 40 or 17 x 45. Original wheel/tyre combo was 14 x 75 x 165, so will be trying to match that total circumference as closely as I can to maintain speedo accuracy. All those sizes are very close in measurement of circumference, so any size I use should require very similar diff as one complete turn of the rear wheel is within less than 1/2 inch of any of the tyre options.