Yea they use large rim sizes for the outlaws, probably so there is a low chance of the rim slipping. We have sandy mud here, sometimes black sand out in the woods but similar. There was so much grip that our 350 warrior couldn't spin the tires, either it was moving forward, or doing wheelies. They are amazing fun in the snow, I drove up a ~6ft steep hill with a good 4-5 ft snow drift over it, took a few attempts, but when I was done it looked like someone snow blowed a path lol.

I know the 28in specs the best since thats the ones we bought new, top tread was 1.25in, side wall tread went to 1.5in. Tread is also scooped slightly like a paddle tire. The only time I've seen these tires load up was in thick nasty clay, but that basically doesn't exist in my area. Also for utility work (like pulling more than you really should in loose sand) can be problematic because it digs down so fast when it does spin. Dry sand I'd say is it's weakest area.

My experence goes way back before the outlaw 2 or outlaw 3 existed. The 25in tires I had used 12in rims, the 28in tires also used 12in rims. Newer ones I think use 14in+.

I can't find the artical, but when they were first introduced to the market, they were stacked up against the two or three most aggressive tires and tested in several conditions. If I remember right the outlaws were not the fastest machine though stuff, but it has the best "pull" though the muck.

Anyway, here's a couple screen caps of my 250es in some nasty muck. My dad with a 4x4 rincon wouldn't go though the same hole, nasty clay stuff. My front tire was (still is) garbage for steering, so the first thing it did was throw me to the right trying to go up the bank. At the very end I had to push a little to get up the slime hill, it was too hard/wet for the tires to grip into. My net is too crap to upload videos sadly. Vid was from Trikefest 2014, Indiana clay.

Also the big thing about the 28in outlaw back then was that it actually measured 28in tall. If your tire is actually 25in and you have 2in clearance, 26 will fit no problem, 27 might squeeze by but depends how close it actually gets, might rub slightly. Could always bend fender holders etc slightly to get the clearance if needed. I'd say 26 is a pretty ideal size though because of gearing and such. One thing to remember is you'll want 25-26in tires up front too, and it needs to bee a grippy steering tire (not a mud tire) so you can control the beast. My experience with aggressive tires on a 3 wheeler is that it can sling the front tire around if it's crap for steering. Basically in the case you steer with your weight and can screw you over in some nasty stuff.

Here's a video of the outlaw3, way different size range than you're looking for, but besides being way too high gearing for the tires, that clay was some nasty stuff. Kind of funny the guy kept mentioning something about a 300 doing better. I think lighter the machine, the better the outlaws do. I suspect the large rims is to have less flotation.

Also here's a 250es with way too big of tires lol. I'd say 28-31in would be about the max for the machine. It's floating too much to grip the bottom I think. You can see the wheelie problem though and the steering problem (driving with his weight). Makes me want to swap the 28's to my ugly 250es and remove the racks and such lol. I miss those tires so much, ever since I got into Honda the warrior has just been sitting. Need to get it fired up and checked over and sell the machine (it has 25in tires now). Probably would have to drill another set of holes in the rim for the Honda bolt pattern, unless the warrior was the same bolt pattern.

Not trying to say outlaws are the best tire ever made, but from everything I've experienced, there's been nothing like them. Never had the money to buy another super aggressive tire to compare them myself though. Btw for clarity, both the 25in and 28in outlaws I had were the original design. By no means heavy or stiff, I guess the newer the tire design, the more it's designed for like a heavy side by side.