Two Douglas Kart racing wheels with hubs with 17mm bearings. These bearings could easily be changed to 5/8 if need be. My best guess is that these are metric wheels on metric patterned hubs but I don't have an American pattern to compare it to. Tires are Bridgestone YHC and have lots of life left in them. Perfect for kart racing, wagon, barstool, even drift trikes