Recently I bought some really versatile wheels from a company called CamOnWheels CW2. I really like these wheels because of their versatility. You can mount them on just about anything you can think of. I built a DIY PVC dolly and drilled 1/4 inch holes on the ends, where the skate board wheels would go.
They are versatile enough to be used in multiple types of projects such as creating your own dolly or any other DIY project.
The main support is made of zinc alloy and the ball bearing is made of carbon steel with injected polyamide. The thread inside the main support is 8mm. They run on 1” 1/4 size PVC pipes or bigger. When using a 5/16 or 8mm screw, you can run them on 3/4 size PVC. One wheel diameter is 22mm and 42mm from center of wheel to center of other.