Going to try making my HF tire more user friendly. I need the axle  diameters to do so. If  same I will just measure the rear one. Thanks
Wayne

Without breaking out the micrometer - rear axle is 20 millimetres. Front is 25. That'll be 25/32 inch and 63/64 inch if you're reading this in black and white. 

Michelle, are you certain about that?
I know the shoulder {at the ends of the front axle} are larger, but I thought the Inside diameter of the bearings were the same?

Ride safe, Ted

Update; Michelle; I looked at images on Ebay and I think you  are correct.
             kzz1king; What are you thinking to do? I'm wanting to do something similar to my HF tire changer.

BEARING DIAMETERS ARE AS FOLLOWS;

FRONT

601B6005UU   BEARING-BALL,#6005UU

Dimensions - d (inside diameter)   25mm
Dimensions - D (outside diameter)   47mm
Dimensions - B (width)   12mm

REAR
601B6304UU   BEARING-BALL,#6304UUC3

Dimensions - d (inside diameter)   20mm
Dimensions - D (outside diameter)   52mm
Dimensions - B (width)   15mm

with that said, and to make the H/f tire machine happy, you want a 3/4" threaded rod, which will work on both wheels just fine.
The H/F I have, is actually threaded 22mm, but a 7/8" bolt, with a wrap of teflon thread tape, will thread into it...
I made a screwed in adapter for mine, and a pals, by elding a 3/4" SAE nut, to the head of a 22mm bolt, and it allows me and him to insert a piece of 3/4" all-thread, to use as a center post... with common nuts and washers.

Thanks MOB. That's what I will do.

 Update. Following Mobs direction on HF mods improved the process tremendously.  I used to just stick a old lug wrench in the center. The Mojo lever likes the solid center much better. Great mod.