Roll out is the size is the circumference of the tire. Ours were always marked the same also. We also use beadlocks so blowing them up to 35 psi to seat is not necessary. We have never had a issue pulling 1.15-1.17 60ft with roll out being a little off. When you start hitting it harder and start dropping in the 1.0s 60fts the Roll out will become very important. We cover our tires and sometimes on hot days will even jack the rear end up and pull the valve stem and reinflate before the next round. This eliminates the sun from growing the tires. This might just have been bad luck, but this has been a back to back issue for us with Mickeys. Now if I was running a 33x10.5 Mickeys would be all I would use. They have still yet to provide me with a 34.5x17x16 that I was able to race, and don't mind keeping your money. I am going to note again this is out of 3 sets and is back to back issues. Goodyears All The Way, I have heard good things about hoosiers though, I might give them a try.