Hub Adapters For Wheelchair Motors

I am looking for some type of Hub Adaptor to increase the diameter of the wheels on a dragster I made for my grandson. I have googled for many hours and have not found a solution. I was hoping I could buy something off the shelf, but I may have to fabricate something. I believe the motors have a 5/8" keyed shaft and I am wanting to go to 16 to 20 inch diameter wheels. I am attaching a picture. I need info on the hubs and then info on the wheels that would bolt to the hubs. Any help would be greatly appreciated.

Hello @Poomp and welcome to the RobotShop forum,

Unfortunately, there are no wheels of that size available in the store. However, there is a 5/8" key hub:

So I would recommend looking for wheels that match the hub pattern

Thank you! Upon doing more research, it appears the wheelchair motors shaft size may be 17mm not 5/8".

Does anyone know if there is a standard shaft size for wheelchair motors?

The closest one I could find is this one:

Poomp, I am dealing with the exact same issue. Making a beach wheelchair using lightweight folding wheelchair frame and motors from a jazzy. For the life of me, I can’t find a 17mm keyed hub that would fit golf cart wheels bolt pattern. I did find 5/8” keyed hubs and considering boring them out a little to 17mm… any luck on your project?