According to the newest operators manual available, the dimensions Deere gives are from the center of the machine. They are measured out to the inside of the unloading auger boot. It is 25.1' for the 22.5' auger and 27.7' for the 26' auger (wondering if it's a misprint and supposed to be 28.7', but I don't have one to measure). If you measured to the outside of the boot, you would easily gain a foot. I measured a 22.5' tube on a new 9870STS and from the center of the turret to the end of the tube (not including the boot) was right at 22.5' with the auger folded back. I would say the 22.5' and 26' measurements they are using are the tube itself. I remember Deere saying in one of there competitive comparison bulletins when the Claas 500 series came out, that Deere's 22.5' auger was the same as Claas's 26' auger.