I just picked up a bunch of Michelin 1100r20 XL's from Berg in Fayetteville, NC. You have to check often with them as they do not stay in inventory long...

They also get in Goodyear G177 fairly often, they don't stay in the warehouse long either.
I looked at a M109 that came out of GA recently that was running on Firestone 1100r20 radials (have to get the number off them) that has a copy of the Michelin XZL tread pattern but with a much harder compound then the Michelins. They will wear better as a result, but they made the truck "twitchier" to drive than any I've driven with the Goodyear or Michelins mounted.
Tire life on these trucks is highly dependent on inflation, useage, and (for the front) if you have a winch mounted... I've gotten 15k miles out of a set of Titan 900x20 NDT (T-Hawk) on a rear of truck that ran up and down the Interstate from FL to GA on a regular basis hauling generators and such, but I went through two sets on the front axle (non-winch truck) in the same time period.