3.90's and 4.10'-no way.i've had trucks with the same size tires(so it said on the sidewall)that were 1" difference in height and it was hard to get it back into 2wd after just a few feet.if you are running 2 different size tires and 2 different ratio rears do this.diameter of smaller tire divided by diameter of larger tire-smaller ratio divided by larger ratio.get them as close as possible and it might work.