These are very good wheels but I'm dumb so they didn't work out great for me. I bought these wheels and 4mm universal hubs. These wheels don't work with the universal hubs that I used, so I had to drill holes in the wheels. Also, make sure to keep track of both of your tires. I lost one of mine and couldn't use the other tire either since it would be uneven. I just duct-taped around the edges to add some traction. I use these wheels on a robot and they still work pretty well even with my constant stupidity throwing everything I have at it. However, these wheels are very nice quality and very stable, even with my duct tape wheels. Just don't be stupid like me.