I measured them with a digital caliper and the bearing diameters were accurate. A previous set I ordered from another company said they were standard sizes but it was actually metric and didn't work at all. The bore on this bearing is exactly .750" and since my heavy wagon axle was also exactly .750" I had to grind it down to get the bearing to slide. It was exhausting, but there seems to be a lack of spare parts for each wheelbarrow. Warehouse? hard to find. Wheels? (no wheels, but tires) not to be found. Tires? Most of them belong to the homeowner class. The only heavy duty wheelbarrow tires on the planet (yes, on the planet) are the Kenda K371 bias trailer tires.