Being that this is a new sport to you, picking the line and amount of gearing/speed or lack thereof is more important then tire size. Takes a little time to figure things out but always go at your own pace.
It is the difference in circumference that affects the low end pull most, not tire weight.
This has been a long discussion with disagreement for years.
For several reason I would say with 26"s true.
Yamaha axles have their limits, and if you add c.v.t. mods for a higher ratio, which I am betting you will want with 26" tires, the heavier secondary spring then needed will make the axles the weak link in the drive line. I learned with stock axles, not to go bigger than 26"s, a purple spring.
This will be enough for you stock 450, and stay within set-up limits for a good all around set-up. There are limits.
And it changes the axle angles.
If you are splashing through mud puddles as the pictures indicate, not buried in thick peanut butter mud, just hit them hard and power through. I would rather have 26" tires with a stock suspension, than 25" tires with a slight lift kit.
Remember you are riding a small bike with different limits.
The leader of the ride was using a 16 grizzly 700 with 28s.
I understand the limits of my bike, but at the same time the available lines to my bike were certainly less than the rest of the group's which made me slower. I'm not saying I expect to be as fast as seasoned riders on night one, but I will need to learn to trust my skid plate if the clearance and ride height is going to be an issue riding these Rocky trails.
Thanks again. I really enjoy learning first. Helps be a better rider when you have some logic behind your ride.
One of our members not on much these days added aluminum skip plates for the rock in AZ. He would wear out these every few years hitting rock. He was fast and a hell a rider with picture to prove it.
Look in this thread and see his avatar, he didn't lose it and rode through the wheel stand.
Many rode O.G.'s back in the day, probably the best overall tire to put on a griz, but not the least expensive.
I will not change, and these are about to be gone.
They work well in most riding conditions, from in the desert to high mountain snow riding.
There are many different Maxis tire models, MANY!
Then there are 3 (at least) different Big Horn offerings.
Different models are restricted to certain sizes (not all sizes come in all models). I think you pictured the 3.0 tires, while I have experience with the O.G.s (originals). Mine have white letters, the others don't.
Look through what is listed here for sizes;
I wouldn't consider running the 2.0's, there are many better choices. This is based upon my area trail conditions.
Then R.M.A.T.V. doesn't offer the tire you pictures, so you found someone else's listing.
I use the O.G.s for several reasons.
These are heavier ply,
The lugs are heavier,
And the lug spacing is tighter.
These tires where, if still not, the stock tires for the popo RZR machines which are much heavier than the Grizz.
They performed extremely well on the heavier machine, so I got some for the Grizz, then learned they work great in all the conditions I ride.
THEN it turns out the 26" O.G.s are true to size, which then was important when learning the c.v.t. system and for getting accurate numbers.
That may be the stock size wheel these days for a popo, I haven't looked in a couple years.
The R.Z.R.'s use to have 12" wheels standard but that might have changed. And you may have to buy new now.
My point was the O.G.'s were strong for the 900# plus machines, plus two fat popo people and a bunch of their gear and beer beating around in the rocks around here, so I put some on the Grizz. This area has hundreds of popo rental machines and not once did I see one of these on the trail parked by a flat tire....and the beating I give my 660 has not hurt a tire either.
One time I jumped the grizz high into the air to clear a 10' water board (ditch) and landed on a big sex-stone. The right rear wheel bent in toward the axle for 6"s along the inside wheel lip breaking the bead, so I took the wheel off the bike and used another rock to beat the wheel lip back out to 'close to round' and with a battery op. compressor aired the undamaged tire back to 11# without further work to this day. (both are still on the grizz today)
The tire is tough and takes a beating that bent the wheel, and the material the stock wheel is made of allows for some bending without cracking.
Maybe one of the other members riding with me that day will link the video taken of me using the rock on the wheel. I was 20 miles in either direction from a town and these parts kept me going with only a minor delay.