Redesigned, based off the original Rockwell wheels, these are 3D Printed from solid PLA Plastic. The rubber tires which break down over time aren't needed for the sander to function properly. I made some improvements to the wheels, like increasing the thickness of the inner diameter to include what it would have been with the rubber tires. I have rounded the inner corners to add support as well as prevent dust and grit build up. Lastly I made it so you can use your own bearings if you want. Many times the old bearings are still in good condition or just need to be repacked with fresh grease. For that reason, these wheels are designed with a bearing stop ring inside to let you know where the exact center is for press fitting the old or new bearings. Also, if you do order bearings, they will come loose as some times the shafts with the old bearings can be difficult to get the bearings on and off. I recommend you place the bearings on the shafts first to and then press fit into the wheels using a vise or arbor press to avoid damage to the wheels. Thanks for supporting my business!