Aluminum filled epoxy 10lb kit (1 gallon) = $100
Urethane foam kit 1 gallon = maybe $100
Black tint for urethane = $20 highly concentrated, goes very far
Blank of wood turned on a lathe to make a master tire model = going labor rate in China or Taiwan
Some wood to make a box and a can of mold release and your good to go into production.

How expensive is it to make a new tire mold?
That’s the direct way to make a simple two part mold to cast a tire. You can make it more complex and more expensive from here. Just don’t make excuses for RC manufacturers please...