The rear wheels are 6 inch casters that have seen better days and are heavily stained. I cleaned them and coated them several times with black rubber to give them a renewed life and also painted the hubs to prevent rusting and remounted them.
I recycled these 4 inch wheel hubcaps from a different wheelchair, whoo I have Rims ! I will spray them to match the body.
Here everything has been assembled again. The rear casters look much better now and have much more grip instead of sliding. The front hubcaps now match like they belong there. :)