That bad boy has enuf power that you prolly wont see much of a diff with 26"ers. But you only get half an inch of extra clearance. BUT, you get a deeper lug.

 

As you can see I have bearclaws on my bike. they are 25" and I wouldnt go any bigger.(these are the third quad these tires have been on) I would have to ride a kodiak 450 with the 25" then ride a kodiak 450 with 26" to really see the difference I guess.

 

I have done a lot of research on the exact same thing and I'm doing what camo-man has done - 26" ITP 589s.

 

I had looked at the 25" Mud lights but I wasn't impressed. Yesterday I looked at the 26" and wow!!! The dealer says he can't keep em in stock. They are way lighter than the 589s and look to have the same tread depth (as the 25" 589s).
Rob says that the 589s are like having mountain magnets for wheels since they are so heavy but they make the ride way more harsh since they are so hard.

 

Naw,,,My 26 589's ride nice, If you run 6-10 psi they will be real harsh, I run about 4-4.5psi,
Now keep in mind it depends on the rider, speed, and terrain on how you guage tires,
I trail ride, bust new trails, ride in streams and mud , and I think this tire is perfect, What ply are the mudlights?
I like an agressive tread and a 6 ply tire which means it is stiffer, but then again they everyday stuff in the woods
long thorns and things of that nature will hopefully not not flatten my tire as easily as a 2 or 4 ply. It is a trade off.
If that Mudlights are a 6ply and you like the pattern and are in your budget, that is your ticket..

 

with the 26'' 589 is there any power loss. I have a 2004 Kody 450

 

There shouldnt be any power lost.