OK, you're going to think I'm crazy, but this is from a guy at work...so thats my disclaimer
I have a set of Mud Lites on my cat. The left rear tire feels like it has a flat spot in it and has somewhat of a slow-leak. When pressurized, it lessens the feel of it, but if its been sitting for a while and I take it out on the pavement, it goes flop-flop-flop on this one spot on my tire.
That said, I was complaining about this to a guy I work with and he said i had some sort of cut on the inside of my tire where one of the treads likely is and that putting a bit of sand in the tire should cure this.
Should I give it a whirl? If not, I need a used 26x12x12!