They seem to be getting harder to find. You could post a wanted ad in the classified section as someone here may have a set they are looking to sell. Outside of that, you can scour the Internet for a set. Try searching for Goodyear Super Terra Grip or Titan Tru Power A/T's. Just watch the ply rating because it will make a huge difference in ride quality. Overall, the Titan Tru Power A/T's (or Carlisle Tru Power A/T's) seem to ride better than the Goodyears.
You can also call your local Max dealer or the Max factory directly: Amphibious Six-Wheel Drive All-Terrain Vehicles: MaxATVs - Call 1-800-255-2511
If you have had any trouble with popping a bead off, now would be a good time to upgrade to the k-lock wheels as well. They have a deeper bead rolled into the wheel that helps the tire bead stay in place, allowing you to run lower pressure for a more comfortable ride. You can get them from your local dealer or the factory as well, and you may be able to get them with the tires already mounted.
will the tires in the like work on the Buffalo 6x6
tires-easy.com - Details: Carlisle Tru Power 26x12.00 -12 4PR
where can you buy k-lock wheels at?
Yep, those tires will work. They will ride hard, but they'll work out for you just fine.
You can get lock wheels directly from Recreatives. Amphibious Six-Wheel Drive All-Terrain Vehicles: MaxATVs - Call 1-800-255-2511
By the way, that's a really nice Buffalo Truck you have there......I love those things!
"Looks like you have a problem with your 4 wheeler........you're missin' two wheels there"