think if you set the tire spinning up differently (like with the tire clamped inside a cup / bowl and spinning without wobbling and with the drill mounted in a vice at an angle so it desnt moe and you have both hands free to pour ) so you can pour the glue in from a small can it should work better and faster , would make less of a mess too if youre aim is good enough
Thanks for showing your science project. I use hotglue in lots of ways, it is a great material. For a tire it seems much too dense. It might make it work better if you mix it with another less dense material, like perhaps small air filled balls. I need to make some low profile solid tires, and am thinking to take some 10in OD with 4in ID solid tires and cut out the inside to fit into 8in ID wheels. Really would like to know what is inside these tires, guess I will find out as no youtube video shows one.
if he can 3d print the rim he could make a temporary rim with funnel too and use a 2 part type silicone to fill the tire and after drying cut away the rim , cut the funnel part off the silicone cast and put the actual rim in it , he could allso cast it in two halves (left side right side) , using a 3d printed negative mould and with some effort bend them up to stuff them in the tire before mounting it on the rim