I used these wheels as a complete set on a 2007 Scag SFZ52-BS26. The mower has approximately 400 plus hours of use. The original wheels were pneumatic with bush bearings. The Marathon wheels with 1/2" bore ball bearings were a perfect match. After installation I mowed about an acre of grass. My impression compared to the original was that the wheel wobble was much more responsive. Rolling resistance was lower, ride slightly bumpier, the original air wheels had problems holding the air in them and wanted to hang in the grass and not rock when changing direction at first.