LT250F Quadrunner 4x4 gearing

OK, here it goes. I have a 2002 Quadrunner LT250F. This thing is completely stock and get this only 50 miles on it. The guy bought it, rode it twice and parked it in garage. OK.....it runs great but has staggared tire sized. 25 in rear and 22 in front. I want to put some upgraded tires but want to run all 25 or 27 not sure yet. How do I go about changing the gears either in front diff or rear diff to match so I do not have problems with different gearing.

HELLP