dropping radius arms on narrowed axles

[Hedd_Jones]

For what its worth, and in the interests of not spending money, why not just use 20mm bolts? 

Often 20mm bolts are a nice fit in 3/4 clearance holes. If not some gently tickling with a file will have a very nice fit indeed. 

Grind all the shite off the head and only a saddo like me would know they were metric rather than imperial, and you might actually have a socket in your socket set that fits.

And you can practically walk into most agricultural merchants and but them off the shelf.