Commando tires (tyres)
I don't believe any manufacturer has radials similar to the original size 4.10x19. What's commonly available in biased ply - Avon classic Roadrunner 4.10Hx19 made in England, Dunlop K81 4.10Hx19 made in Japan and Avon Supervenom AM18 100/90-19 front or rear and/or Avon new Roadrunner AM20 90/90-19 front only. The biased tires are all tube type which is what you need with spoked rims.
To use much larger tires such as what's available in radials will require modifications to rim widths and suspension clearances. You might want to get some opinions on this before going this direction as the handling could be greatly impacted.