We have tested them in the desert of Las Vegas. They have completely impressed us and we have had no issues with them at all. They are a bit heavier than your normal 6ply but they don't claim them to be a race tire. What they told us was that they were designed to be the toughest tire out there and I believe they are. We sell many of them to a couple power line companies in UT. and hunters in UT as well. We also have a gas line company testing them now. They recommend running air in them but said they have recorded over a 1000 miles on a set without air while in the testing stages of the tire. They also told us they have more sizes coming because of how popular they have become. We have been recommending to our customers to run the same size tire 27x9x14 front and rear to save some weight and cost rather than purchase the 11" wide. When installing the 9" on the rear wheel it makes it a bit wider than the front and works well. For what's it's worth we are very pleased with them. We have found the price is not bad if all your flat issues are gone, in fact we believe we have already saved money.
The RP SOF tire is a very nice tire.. It does exactly what it was designed for and that is get you from point A to point B without air if needed. In fact we have heard many people using them actually don't run air in them at all. They are also a great bunch of guys to do business with.