You can find the B-534 texture in the tehtures folder, and edit it the way you like.
Than you just switch the image mode back to "indexed", and save it over the original file
Thanks for the tip Warhawk, but it's not really practical IMO to edit the mod's texture file, as it would require a change every time we select an Avia with different color wheel hubs. Plus, it would still exclude any efforts at individual weathering.. paintchips, mud stains, etc. Sure, it could be done to a certain extent, by keeping a variety of hub textures on hand and swapping them in and out of the texture folder; but this method is ultimately defeated should we want a mission with mixed squadrons.. i.e; squads with red hubs, green hubs, yellow hubs etc.
So for now, the only practical way to display all those little skinning details that distinguish each Avia hub, is to remove the Avia B-534 folders and revert to the default wheels, which will allow the skinner's work to be visible. Sometimes I wish the Avia had retractable landing gear
Of course that's not to say that a practical solution won't come about in the future; there are some pretty sharp minds in our community, Jero included.