You will find most Grizzly owners go with a 26" tire size. Most places that sell the tires will also sell the proper size rim to fit your machine. Also the issue of total weight for the tire & rim should be taken into consideration. If you go with a real heavy tire, a clutch kit would be needed to get the proper shifting back, (example) 26"rear 589 = 33 lbs each, 26"rear Mudlite = 25.9 lbs each, 28"rear Highlifter Outlaws = 38.7 lbs each, and 28" rear Super Swamper Vampires = 40 lbs each. So the taller/bigger tire does indeed weigh considerably more then the stock size 25" recomended. You would be safe going with a 26" Mudlite or any other 26" tire in that same weight catagory without having to do any clutch mod. I ran 26" 589's on my Kodiak for three years without any clutch mod and never had any problems. I run 26" Mudlites on my Grizzly now with a Dalton clutch kit and the only difference is a better low end response. Could I have just ran the Mudlites without the clutch kit? You bet... The Grizzly has more then enough "balls" to power the tires. You wont gain much ground clearance with a 26" tire size, even tho its 1" taller divide that by two(1/2 circumfrence) and you only get 1/2" total height gain. There are many great tires available today and the choice is difficult, I guess it all depends on your own personal preference.