I learned this years ago building race car models. Great looking bodies and decals and tires that looked like Christmas wreaths. When I found a good set of tires, I would duplicate them and cast as many as I needed.
I thought I read somewhere that I should replace the smallish Eduard D.III wheel/tires with more correct size from the Eduard D.Va. I also needed some British wheel/tire replacements for another project. You will need kit parts to be duplicated, Silicone mold material and resin casting material. The later two available at a good Art's/Crafts store.

I went in the stash and dug out the appropriate parts need to use as masters. I mounted them to some square rod and taped up the ends. Once finished, I can return them back into the box.

Above is the Eduard D.Va, Camel and Roden SE.5a.
I glued them into a suitable container, mixed and added the mold material.

After the allotted time per the directions, I removed the mold and masters then mixed the casting material and poured it in working quickly and poking a small stick in to remove any trapped air bubbles.

I have replacement wheels in resin and can return the kit wheels to their rightful boxes.