Ihave several Gilbert steamers that I run. I have a few diesels but I've never tried to run them.
Try the link below. They have parts diagrams and some parts. Modern traction tires of an appropriate size should work. I have not had good luck with new old stock.
This is another interesting site if you are into Gilbert
Banks, Proud member of the OTTS TCA 12-67310
I may not have every thing I desire but the LORD has come through with what I need