If I had a set of 12mm wheel hubs, is there any way to mount them to my bug? Can I get a bearing with the same ID of the 15mm bearing but the OD of the axle hubs?

If you are asking about the standard PL ABS type wheels then the 12mm and 15mm bearings are exactly the same other than the ID measurement. You should be able to pop the 12mm out and insert the 15mm no problem. All you need to do is purchase the internal spacer.

If your wheels are not standard size, then you will need to check to see what is available in those sizes.

You only need to change wheels if you go from the 12/15mm to the newer 20mm wheels as the OD of the 20mm wheels is much larger.

We have all of the parts you need in stock. We also have special custom made spacers that will allow you to mount the 20mm wheels onto 12mm or 15mm axles.

Hope that helps.